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BOOK 6 19. 1.B2 1 c. 1 

BALLOU # COMPEND OF EQUINF 

ANATOMY AND PHYSIOLOGY 




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Tensor palati. 

i 

J ' Levator palati. 



Orbicularis oris . 

Pterygo-maxil- ) 
lary ligament j 



Mylo-hyoideus . 

Os hyoides . 

Thyro-hyoid \ 
ligament j 

Pomum Adami . 



Cricoid cartilage 
Trachea . . . 




Glosso-pharyngeal n. 
Stylo-pharyngeus. 



Superior laryngeal 
n. and a. 



External laryngeal n. 
Crico-thyroideus. 

Inferior laryngeal n, 
(Esophagus. 



Fig. 15. Holden's Anatomy. Muscles of the Pharynx. 

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? QUIZ-COMPENDS. ? No. 12. 



COMPEND 



OF 



EQUINE ANATOMY 



AND 



PHYSIOLOGY. 

BY 

WILLIAM R. BALLOU, M. D., 

PROFESSOR OF EQUINE ANATOMY AND FORMERLY LECTURER ON PHYSIOLOGY, NEW YORK 
COLLEGE OF VETERINARY SURGEONS; INSTRUCTOR IN GENITO-URINARY SUR- 
GERY, NEW YORK POLYCLINIC; SURGEON EELLEYUE DISPENSARY; 
LATE HOUSE SURGEON, EELLEYUE HOSPITAL, NEW YORK. 



WITH 

TWENTY-NINE GRAPHIC ILLUSTRATIONS 

SELECTED FROM 

CHAUVEAU'S "COMPARATIVE ANATOMY." 



PHILADELPHIA: 

P. BLAKISTON, SOX & CO., 

i o i 2 Walnut Street. 
1890. 




Copyright, 1890, by P. Blakiston, Son & Co. 



PRESS OF WM. F. FELL & CO. 

1220-24 SANSOM STREET, 

PHILADELPHIA. 



TO MY STUDENTS AT THE 

NEW YORK COLLEGE OF VETERINARY SURGEONS 

THIS LITTLE WORK IS DEDICATED, 

IN THE HOPE THAT IT MAY ASSIST THEM 

DURING THEIR LIFE WORK, 

WITH THE KINDEST WISHES OF 

THE AUTHOR. 



PREFACE. 



The popularity of this series of " Compends" demonstrates that 
they supply a long felt want. From a considerable experience as 
a quiz-master of medical students and a teacher of anatomy, the 
writer has seen the benefits of these, and has endeavored to supply 
for students of veterinary anatomy and physiology a work which 
would answer their needs not only as a text-book, but also for work 
in the dissecting room. 

While, in the main, the standard work of Chauveau has been 
followed, the works of Strangeways, Gray and Quain have been 
consulted. In the section on Physiology the late works of Flint, 
Meade, Smith and Jeffrey Bell have furnished the greater part of the 
data, and to them indebtedness is due. Many of the chemical 
analyses have been taken from Charles. 

Lack of space necessitated a condensation of some subjects to 
narrow limits, while others have been merely alluded to. The author 
trusts it will meet the same cordial welcome from the veterinary 
profession which the other works of this series have received from 
their fellow-workers in medicine. 

My acknowledgments are due to Messrs. D. Appleton & Co., the 

publishers of Chauveau's "Comparative Anatomy of Domesticated 

Animals," for their courtesy in supplying the illustrations I have 

used. 

WILLIAM R. BALLOU, M. D. 

220 East 3 1 st St. , New York City. 



CONTENTS. 



PAGE 

Anatomy, 9 

Physiology, 9 

Anatomy, Divisions of, 9 

Osteology, 9 

Bones, Varieties, 9 

Structure of, io 

Vertebral Column, 1 1 

Head, 13 

Face, 18 

Fossae of Skull, 23 

Hyoid, 24 

Bones of Thorax, 24 

Anterior Extremity, 25 

Posterior Extremity, 31 

Arthrology, 37 

Classes of Articulations, 37 

Structure of Articulations, 38 

Articulations of Vertebral Column, 38 

Lower Jaw, 39 

Hyoid, 40 

Thorax, 40 

Anterior Limb, 41 

Posterior Limb, 45 

Myology 5° 

Structure of Muscles, 50 

Varieties of Muscles, 50 

Appendages of Muscles, . 50 

Muscles of Face, 5 1 

Mastication, 53 

Hyoid, 54 

Tongue, 55 

Palate, 55 

Pharynx, 56 

Trunk, 57 

Inferior Cervical Region, 57 

Back, 62 

Thorax, - 63 

Abdomen, 65 

ix 



X CONTENTS. 

PAGE 

Inguinal Canal, 66 

Muscles of Anterior Extremity, 66 

Pelvis, , 72 

Thigh, 75 

Leg, 77 

Tail, , 80 

Angeiology, 81 

Pericardium, 81 

Heart, 81 

Arteries of Anterior Extremity, 85 

Head and Neck, 89 

Trunk, , 93 

Posterior Extremity, 96 

Artery, Pulmonary, 98 

Veins. Structure of, 98 

Head and Neck, 99 

Anterior Extremity, 99 

Abdomen and Pelvis, 101 

Posterior Extremity, ... 102 

# Pulmonary, ■ . . 102 

Lymphatics, 102 

Neurology, 103 

Nervous System, Structure of, 103 

Spinal Cord, 103 

Membranes of, * 103 

Brain, Membranes of, 105 

Medulla Oblongata, . - 105 

Pons Varolii, 106 

Cerebellum, 107 

Cerebrum, 107 

Ventricles of, 109 

Nerves, Cranial, in 

Cervical, 115 

Brachial Plexus of, 115 

Lumbo-Sacral Plexus of 117 

Dorsal, 118 

Sympathetic Nervous System, 118 



Viscera, 120 

Digestive System, 120 

Mouth, 120 

Tongue, . . 120 

Palate, 120 

. Teeth, 120 

Salivary Glands, 122 

Pharynx, 122 

GEsophagus, 122 

Abdominal Cavity, 123 

Stomach, 123 

Small Intestines, 125 



CONTEXTS. XI 

PAGE 

Digestive System, Caecum, 127 

Large Colon, -. . 128 

Small Colon, 128 

Rectum, 128 

Anus, 128 

Liver, 129 

Lobes, 129 

Fissures, 129 

Ligaments, 129 

Parenchyma, ' 129 

Pancreas, 131 

Spleen, 132 

Peritoneum, 132 

Respiratory Organs, 133 

Larynx, 133 

Cartilages, 133 

Articulations, 134 

Muscles, 135 

Trachea, 136 

Bronchi, 138 

Lungs, 138 

Pleura, 139 

Thorax, 140 

Mediastinae, 140 

Ductless Glands, 140 

Thyroid, 140 

Thymus, 141 

Urinary Organs, 141 

Kidneys, 141 

Supra-renal Capsules, 144 

Ureters, 144 

Bladder, 144 

Male Genitals, 145 

Testicles, 145 

Descent of, 146 

Vas Deferens, 147 

Vesiculae Seminales, 147 

Prostate Gland, 148 

Urethra, 148 

Penis, 149 

Perineum, 150 

Female Genitals, 150 

Vulva, 150 

Vagina, . . 151 

Uterus, 152 

Oviducts, 153 

Ovaries, 153 

Mammary Glands, . . 155 

Organs of Special Sense, 155 

Smell, 155 



Xll CONTENTS. 

PAGE 

Organs of Special Sense, Nasal Fossae, 155 

Nostrils, 156 

Taste, 157 

Papillae of, 157 

Nerves of, 157 

Auditory Organs, 157 

External Ear, 157 

Cartilages of, 157 

Muscles of, 158 

Canal of, 159 

Middle Ear, 159 

Internal Ear, 161 

Eye, 162 

Orbits, 162 

Tunics, 162 

Humors, 162 

Muscles of Lid, 165 

Globe, 165 

Appendages, 166 

Blood Supply, 167 

Skin and Appendages, . 167 

Hairs, 168 

Hoof, 168 

Physiology, 173 

Definition, 173 

Circulation, 173 

Composition of Blood, 173 

Coagulation " 174 

Circulation " 175 

Velocity of Blood Current, .176 

Respiration, 177 

Inspiration, 177 

Muscles of, 177 

Expiration, 178 

Muscles of, 178 

Nervous Mechanism, 179 

Alimentation, 180 

Definition, 180 

Digestion, '. . . . 180 

Food, 181 

Prehension, 181 

Mastication, 182 

Salivary Digestion, 183 

Deglutition, 183 

Gastric Digestion, 184 

Bile, ; 185 

Tests for, 185 

Glycogenic Function of Liver, 186 

Pancreatic Juice, 186 



CONTEXTS. Xlll 

PAGE 

Intestinal Juice, 187 

Faeces, 188 

Defecation, 188 

Intestinal Movements, 188 

Absorption, 188 

Lymph, 189 

Chyle, 189 

Animal Heat. 190 

Secretion, 190 

Definition of, . . 190 

Excretion, Definition of, 190 

Perspiration, 191 

Mammary Secretion, 191 

Urine, 192 

Composition of, 192 

Amount of, in Twenty- four Hours, 193 

Micturition, 193 

Ductless Glands, 193 

Supra-renal Capsules, 193 

Spleen, 194 

Thymus and Thyroid, 194 

Pituitary Body and Conarium, 194 

Nervous System, . . „ 194 

Nerves, Termination of, 194 

Spinal, 195 

Cranial, 195 

Spinal Cord, 197 

Functions of, 198 

Columns of, 198 

Medulla Oblongata, 198 

Pons, 199 

Corpora Quadrigemina, 199 

Optic Thalami, 199 

Olfactory Lobes, 199 

Cerebellum, 199 

Cerebrum, 199 

Sympathetic System, 200 

Special Senses, 200 

Touch, 200 

Smell, 200 

Taste, 200 

Hearing, 201 

Sight, . . 201 

Reproduction, Reference to, 202 




XIV 



EQUINE 

ANATOMY AND PHYSIOLOGY 



ANATOMY. 

Anatomy is the science of organization. 

Equine Anatomy is its study confined to the horse. 

Divisions. 

Osteology, the study of bones ; Arthrology or Syndesmology, of the 
joints; Myology, of the muscles; Angeiology, of the vessels; Neu- 
rology, of the nervous system ; Splanchnology, of the viscera. 



OSTEOLOGY, OR THE BONES. 

These, the passive portion of the locomotory apparatus, are divided 
into long, short, flat and irregular. The long bones are found in 
the limbs and are hollowed out internally ; example, the femur. The 
short bones are about as wide as long, and contain no medullary 
cavity ; example, the tarsus and carpus. The flat bones are found in 
the head, pelvis and shoulder, contain no medullary cavity and are 
not thick ; example, the parietal and scapula. The irregular bones 
have none of the characteristics of the preceding ; example, the hyoid. 

The Eminences of Bones. 

Heads are elevations on the extremities of bones, describing the, 
segment of a sphere ; condyles are segments of an oval figure parallel 
to its large axis ; processes or apophyses when much detached from 
2 9 



10 EQUINE ANATOMY. 

bones ; protuberances or tuberosities are large and round ; lines t crests 
and ridges are narrow and long. 

Cavities of Bones. 

Cotyloid are deeply excavated ; channels or furrows when wide 
and deep ; fissures when narrow and rough ; digital when of the size 
of finger ends ; fossce, sinuses, cells and notches are also cavities. An 
opening in a bone is & foramen, if long, a canal. 

Composition of Bone. 

Bone is composed of one-third part animal matter, giving elasti- 
city, and two-thirds mineral matter, principally salts of lime, giving 
strength. 

Structure of Bone. 

Bones are covered externally by a fibrous, nourishing membrane, 
the periosteum. Microscopically bone is seen to consist of the follow- 
ing parts : the medullary canal, see cavity of long bones ; the Haver- 
sian canals for the passage of vessels ; lacuna, small black spaces 
containing bone cells with little canals, the canaliculi, branching from 
them ; these three structures form the Haversian systems. Lamellce are 
layers of bone under the periosteum or around the Haversian canals. 

The marrow or medulla of bones consist of red or fcetal marrow, 
and yellow marrow. The former is rich in round cells, the latter in 
fat. 

Development of Bone. 

It may be developed from cartilage or 7ne7nbrane. The former 
method is shown in the long, the latter, in the flat bones. 

Number of Bones. 

Vertebral column, 52 

Head, 8 

Face, 16 

Hyoid, sternum and ribs, ?$ 

Anterior extremities, 40 

Posterior extremities, 40 

194 

The ossicles of the middle ear are not included ; the sacrum is con- 
sidered as five separate bones, the superior turbinated as part of the 
ethmoid, the pterygoid as a process of the sphenoid, the parietal as a 
double bone, and the sesamoids are included. 



OSTEOLOGY. 1 1 

THE VERTEBRAL COLUMN. 

The spinal column is composed of 52 segments, divided into true 
and false. 

The true are divided into 7 cervical, 18 dorsal and 6 lumbar. The 
false into the sacrum, of 5 segments closely fused, and the coccyx, of 
from 15 to 18 segments more or less movable. 

Common Characteristics of Vertebrae. 

Each one has a body and an arch, enclosing the spinal canal which 
includes the spinal cord. The body has a superior face, forming the 
lower boundary of the spinal canal, an inferior, two lateral surfaces, 
a head, convex for articulation, an anterior extremity, and a concave 
posterior extremity. 

The arch projects upward from the top of the body, and consists of 
pedicles, lamina, transverse, spinous and articular processes. 

The pedicles are two strong processes projecting upward and sup- 
porting the transverse and articular processes. 

The tra7isverse processes project laterally from the summit of the 
pedicles. They are elongated antero-posteriorly in the cervical, short 
in the dorsal, and long in the lumbar regions. 

The lamina are two processes uniting above and forming the 
spinous process ; they enclose the spinal cord. 

The spinous processes project upward and backward, from the junc- 
tion of the laminae. They are small in the cervical, long in the dor- 
sal, rough and enlarged in the lumbar regions. 

The articular processes are four in number, two anterior and two 
posterior. The former look upward the latter downward. In each is 
a notch, which, when in apposition, forms the intervertebral foramen. 

CERVICAL REGION. 

Common Characters. 

The body is long and thick and has an inferior spine. 

The spinous processes are a roughened line. 

The transverse br trachelia7i processes are elongated antero-pos- 
teriorly and are in relation to the trachea. They are traversed at 
their base by a foramen, transmitting vessels, the vertebral. The 
articular processes look downward and inward. 

Peculiar Cervical Vertebrae. 

The 1st or atlas articulates with the occipital, has a thin body, no 



12 EQUINE ANATOMY. 

head, two deep concave facets in its place; an articular surface below 
for the odontoid process; transverse process very rudimentary. The 
spinous processes are flattened from above, downward, are elongated 
and show two foramina, the anterior transmitting a vein, the posterior 
the vertebral vessels. 

The 2d or axis is very long, has no head, but, in its place, a pro- 
cess convex and smooth below, concave above, articulating with the 
body of the atlas, called the odontoid (or tooth-like.) The spinous 
process is very elongated antero-posteriorly and divided into two lips. 
The transverse are little developed. 

The5//z has a heart-shaped tubercle on its inferior spine. 

The 6th or tricuspid has a third prolongation on its transverse 
process. 

The Jth or prominens has a long spine, demi-facets behind for the 
ist rib, the transverse processes are single and the vertebral foramen 
is absent. 

THE DORSAL VERTEBRAE. 

The body is short with a projecting head anteriorly, a marked de- 
pression posteriorly, and four articular cavities for the heads of the 
ribs, two in front, two behind. The spi?ious processes are long, and 
flattened on the sides. The transverse processes are short, and have 
a facet for articulation with the tuberosity of a rib. The length of 
the spines increase to the 5th and then decrease to the 18th. The 
1 8th has no facet on its body behind. 

THE LUMBAR VERTEBRAE. 

The body is longer and wider than the preceding, the spinous pro- 
cess is shorter and surmounted by a tubercle; the transverse processes 
are flattened from above, downward, and pass transversely outward, 
the fifth and sixth, and sixth and front of the sacrum articulating by 
facets. 

THE SACRUM. 

The sacrum consists of five segments, closely fused. It articulates 
with the last lumbar and its transverse process in front, the coccyx 
behind and the os innominata laterally. 

It is triangular in shape with a base anteriorly articulating with the 
body, articular and transverse processes of the last lumbar ; showing 
also the vertebral canal, an apex behind articulating with the coccyx, 
two lateral borders articulating with the innominate bones in front, 



OSTEOLOGY. 1 3 

an inferior surface smooth and showing four inter-vertebral foramina, 
and a superior surface showing the spinous process and the super- 
sacral foramina. 

THE COCCYX. 

This consists of from fifteen to eighteen segments, the first three or 
four only are complete, the spinal canal then simply continuing as a 
groove. The first is often consolidated with the sacrum. 

THE HEAD. 

This consists of eight bones, the occipital, two parietal, two tem- 
poral, the ethmoid, frontal and sphenoid. 

OCCIPITAL. 

The occipital forms the upper and posterior portion of the head, 
and is divided into an external and internal face and circitmference. 

The External Face shows — 

The external occipital protuberance, an elevation forming the point 
of the head. 

The occipital foramen (or foramen magnum) below and in front of 
the preceding, a large round opening, transmitting the spinal cord, 
its membranes, the cerebro-spinal vessels and eleventh nerve. 

The basilar process ', a long narrow prolongation passing forward to 
unite with the body of the sphenoid. 

Two sharp crests running outward, the superior, continuing as the 
zygomatic process, the inferior, terminating at the base of the styloid 
process. 

The two condyles which lie on either side of the foramen articulating 
with the atlas. 

The styloid processes, two large blunt projections lying outside the 
preceding. 

The condyloid foramina, lying at the bottom of a fossa ui\der the 
condyles and transmitting the twelfth nerves. 

The Internal Pace shows the foramen magnum, condyloid 
foramen, and a smooth roof for the cranial cavity. 

The Circumference shows — 

Articulations above for the parietal bones, and laterally for the 
temporal. 



14 EQUINE ANATOMY. 

A deep notch closed in by the temporal and sphenoid, forming the 
anterior and posterior lacerated foramina, separated by a ligament. 

Articulations, 6. 

Two parietal, two temporal, sphenoid and atlas. 

PARIETAL (A WALL). 

The parietals form the roof of the cranial cavity, are developed 
from two centres closely fused together and closed in by the occipital, 
frontal, temporal and opposite parietal. 

It has external and internal surfaces, and four borders, superior, 
inferior, external and internal. 

The external surface shows the parietal ridge beginning at the oc- 
cipital protuberance and ending at the supra-orbital process of the 
frontal. It divides the bone into two rough and one smooth portions. 

The internal surface shows depressions for the brain and a marked 
elevation, the parietal eininence, which lodges the confluence of the 
sinuses, the torcular Herophili ; from this point lateral ridges run, 
lodging the parietotemporal confluents. In front it is prolonged by 
the suture between the two bones, the sagittal. 

The superior border is thick and articulates with the occipital. 

The i?iferior border articulates with the frontal. 

The internal border articulates with its opposite. 

The external border articulates with the temporal and forms a 
groove, the parieto- temporal canal. 

Articulations, 5. 

Occipital, frontal, sphenoid, temporal and opposite. 

FRONTAL. 

The frontal (frons, the forehead) forms the front part of the roof of 
the cranium and part of the face. It lies between the parietals above, 
the nasals and lachrymals below, and the temporals laterally. 

It ha^ two surfaces, an external and internal, and four borders, a 
superior, inferior, and two lateral. 

The External Surface shows — 

A median plane surface covered with skin and forming the base of 
the forehead. Two strong processes projecting outward forming the 
orbital arch and articulating externally with the zygomatic process of 
the temporal. An opening in the orbital arch the supra-orbital. 



OSTEOLOGY. 1 5 

At the base of the arch a depression for the pulley of the superior 
oblique. 

The Internal Surface is concave and shows — 

A superior part articulating with the parietal above and joining 
below the crista galli and wing of the sphenoid. 

An inferior part articulating in the median line with the ethmoid, 
and shows two large openings into the frontal sinuses, two spaces 
between the external and internal plates of the bone. It forms part 
of the roof of the nasal fossae. 

The superior border articulates with the parietal and temporal, the 
inferior with the lachry?nal and nasal, and the lateral with the palate 
and sphenoid, forming with the latter the orbital foramea. 

The frontal has two centres of ossification. 

Articulations, 14. 

With two parietal, two temporal, two -nasal, two lachrymal, sphe- 
noid, etlunoid, two palate and two superior maxillary. 

ETHMOID. 

The ethmoid (sieve-like) lies at the anterior part of the floor of the 
skull, and forms part of the roof of the nasal fossae. 

It is divided into a vertical plate, a horizontal portion and two 
lateral masses. 

The vertical portion articulates below with the vomer and the 
median nasal cartilage, forms the median septum of the nose, and 
terminates above in the crista galli, a small elevation on which a 
process of the cerebral dura mater is attached. 

The horizontal portion forms the roof of the nasal cavities, part of 
the cranial floor, and is perforated by a number of openings for the 
passage of the filaments of the olfactory nerves. The lateral masses 
form part of the orbital and nasal walls, are excavated to form the 
ethmoidal cells and show an anterior projection forming the superior 
turbinated bone which is really a part of the ethmoid and considered 
as such. 

Articulations, 7. 

Sphenoid, frontal, vomer, two palate, two superior maxillary. 



1 6 EQUINE ANATOMY. 

SPHENOID. 

The sphenoid (a wedge) serves to connect the bones of the head 
and face, being wedged in between the occipital behind, the ethmoid 
and frontal in front, the parietals and temporals laterally. It is divided 
into a body and two wings. 

The body shows on its internal surface — 

The optic fossa, a transverse depression for the optic nerves, ending 
in the optic foramina, which open into the orbit. 

The sella turcica ox pituitary fossa, behind this, receiving th.e pitui- 
tary body. 

The wings projecting from the body and articulating with the 
frontal. 

Two fissures outside the sella turcica, the inner one lodging the 
cavernous sinus. 

The supra-sphenoidal canals, the upper one called the great sphe- 
noidal fissure, the lower the fora?nen rotundum, the middle opening 
near the optic. 

The External or Inferior Surface shows — 

Outside, the vidian canal opening into the orbit. 

The internal pterygoid plate (pterygoid bone) outside the vomer, 
flattened laterally. 

Its internal face forms part of the pharyngeal wall. 

At its base is found the vidian canal (see above). 

Its apex forms the hamular (hooked) process, passing backward and 
serving for the passage of the tendon of the tensor palati. 

The external pterygoid or sub-sphenoidal process lying outside the 
preceding. 

Above this the opening of the sub-sphenoidal canal which opens 
into the orbit. 

Below two fissures for articulation with the vomer. 

The superior ox posterior border is continuous with the basilar pro- 
cess of the occipital, and on each side forms the inner boundaries of 
the lacerated foramen. Three notches are also seen, for the passage 
of the carotid artery, the forame7i ovale for the inferior maxillary 
nerve, and one for the middle meningeal artery , the foramen spinosum. 

The anterior or i?iferior border shows — 

The sphenoidal sinuses, excavations continuous with the ethmoidal 
plate. 



OSTEOLOGY. 1 7 

The lateral borders show — 

Thin edges for articulation with the frontal, squamous part of the 
temporal and parietal. 

Articulations, 10. 

Occipital, ethmoid, frontal, vo?ner, two parietal, two te?nporal and 
two superior ?naxillary. 

THE TEMPORAL. 

The Temporal is important as forming the bony canals for the recep- 
tion of the organ of hearing, and is found forming parts of the sides 
of the head, face and cranial cavity. 

It is divided into squamous and tuberous portions. 

The Squamous portion is flattened, oval in shape, forming part 
of the lateral cranial wall, and is divided into external and internal 
surfaces and a circumference. 

The External Surface shows — 

The zygomatic process, passing downward and forward," and articu- 
lating with the zygoma ; at its base is found the glenoid cavity for the 
condyle of the inferior maxilla, limited in front and behind by two 
marked elevations. 

The Internal Surface shows — 

The groove, which, with the parietal forms the parieto-temporal 
canal and depressions for cerebral convolutions. 

The circuiTiference articulates with the frontal, parietal, sphenoid and 
occipital. 

It is not united to the tuberous portion. 

The Tuberous portion passes forward and inward between the 
occipital and parietal, and is divided into petrous and mastoid pro- 
cesses. 

The petrous portion shows — 

An anterior face in contact with the parietal. 

A posterior face in contact with the occiput. 

An internal face which shows the internal auditory ?neatus, the 
entrance of the seventh nerve to the internal ear, and the opening of 
the aqueductus fallopii. 

An anterior border separating the cerebral from the cerebellar 
cavities. 



1 8 EQUINE ANATOMY. 

The mastoid portion forms the base of the horizontal part of the 
bone and shows — 

The external auditory meatus, a round opening leading into the 
auditory canal. 

The mastoid process, a round eminence behind the preceding, hol- 
lowed out with cells, communicating with the middle ear. 

The stylo-mastoid canal in front of the preceding. 

Below, the styloid process for the origin of the Te?isor Palati and 
Eustachian tube. 

The hyoid or vaginal process, a small elevation. 

Articulations, 7. 

Occipital, parietal, frontal, sphenoid, zygoma, superior maxilla and 
inferior maxilla. 

THE FACE. 

This consists of 16 bones, viz., two superior maxillary, two inter- 
77iaxillary , two palate, two zygomas, two lachrymals, two nasals, two 
inferior turbinated, one vomer and one inferior maxillary. The 
pterygoid bones are considered parts of the sphenoid, the superior 
turbinated parts of the ethmoid, and the hyoid not as belonging to 
the face. 

THE SUPERIOR MAXILLA. 

These two large bones form the greater part of the structure of the 
face, and are wedged in between the frontal, nasals, zygomas, palates, 
lachrymals and vomer. 

It is divided into two faces, two borders and two extremities. 

The External Pace shows — 

A co7ivex surface ending below in the super-maxillary spine, a long 
ridge continuous with the zygoma. 

The orifice of the infra-orbital canal. 

The Internal Pace shows — 

A flat surface, forming the outer wall of the nasal fossa. 

A deep excavation, the maxillary sinus. 

A fissure which forms the palatine canal. 

A ridge for the inferior turbinated. 

The inferior opening of the lachrymal canal. 

The, palatine process, uniting with the opposite, forming the floor of 
the nasal fossa. 



OSTEOLOGY. 



19 



Afiterior border shows — 

Articular processes for the nasal, pre-maxillary, lachrymal and 
palate bones. 

External border shows — 

Six cavities for the molar teeth, behind them the alveolar tuberosity. 
Below, the small interdental space. 



Fig. i 




LATERAL VIEW OF THE HORSE S SKULL. 

Premaxillary bone; 2, Upper incisors; 3, Upper canine teeth; 4, Superior maxillary 
bone; 5, Infraorbital foramen; 6, Superior maxillary spine; 7, Nasal bones ; 8, Lachry- 
mal bone; 9, Orbital cavity; 10, Lachrymal fossa; 11, Malar bone; 12, Upper molar 
teeth; 13, Frontal bone; 15, Zygomatic process, or arch; 16, Parietal bone; 17, Oc- 
cipital protuberance ; 18, Occipital crest ; 19, Occipital condyles ; 20, Styloid processes ; 
21, Petrous bone; 22, Basilar process; 23, Condyle of inferior maxilla; 24, Parietal 
crest; 25, Inferior maxilla; 26, Inferior molars; 27, Anterior maxillary foramen; 
28, Inferior canine teeth ; 29, Inferior incisor teeth. 



Superior extremity shows — 

A rounded enlargement, lodging the maxillary sinus. 

The infra-orbital canal, running above the molar teeth, ending 
opposite the third molar by one opening, the other extending into the 
interior. 

The palatine ca?ial, between the bone and palate, ending at the 
palatine fissure. 



20 EQUINE ANATOMY. 

Inferior extremity shows — 

A cavity for the tusk, uniting with the pre-maxillary. 

Articulations, 8. 

Opposite, palate, pre-?naxillary , ethmoid, lachrymal, nasal, inferior 
turbinated, zygoma. 

PRE-MAXILLARY OR INTER-MAXILLARY. 

The pre-maxillaries are two bones lying at the inferior portion of 
the face and wedged in anterior to the superior maxillaries and nasals. 

They each show a base and two processes. 

The base shows — 

An external smooth or labial face. 

An internal face, united with the opposite, and showing the incisive 
foramen. 

A posterior or buccal face, forming the roof of the mouth. 

An external border, showing three sockets for the incisors, the inter- 
space and a half socket for the tusk. 

An external process passes upward between the nasal and super- 
maxillary, forming part of the nose and face. 

An internal process forms part of the nasal floor and buccal roof. 
It forms, also, the deep incisive notch. 

Articulations 4. 

Opposite, superior maxilla, nasal, vomer. 

PALATE. 

The palates, two in number, at the back part of the nasal and oral 
cavities, are elongated from above downward, and show two faces, 
two borders and two extremities, a superior, united with the sphenoid 
and an inferior, united with the opposite. 

The External Face shows — 

A superior orbital, inferior palatine, forming the roof of the palate, 
and middle articular, for the superior maxillary, portions. 

The internal face forms part of the outer nasal wall. 

The anterior border shows — 

A deep foramen, the nasal, an articulation for the super-maxillary, 
and a cavity uniting with the sphenoidal sinus. 

The posterior border shows — 

The palatine crest above, and a surface for the external pterygoid 
plate. 



OSTEOLOGY. 2 1 

Articulations, 7. 

Superior maxillary, sphenoid, inferior turbinated, vomer, ethmoid, 
frontal and opposite. 

ZYGOMATIC OR MALAR. 

The zygomas form part of the side of the face wedged in between 
the superior maxilla, frontal and zygomatic process of the temporal. 
It has a base, united with the superior maxilla, a summit, united with 
the zygomatic process, an external face, internal face, anterior and 
posterior border. 

The external face has a smooth portion forming part of the orbital 
margin and a smooth convex facial portion. 

The internal face shows an articulation for the superior maxilla. 

The anterior border joins the lachrymal, the posterior or masseteric 
forms a ridge continuous with that of the superior maxilla. 

Articulations, 3. 

Superior maxillary, temporal and lachrymal. 

LACHRYMAL. 

The lachrymal is a quadrilateral bone forming parts of the face 
and orbit, bent on itself and wedged between the frontal, nasal, 
?nalar and superior maxilla. It shows external and internal surfaces, 
and a circumference articulating with the surrounding bones. 

The external surface shows — 

A superior or orbital portion, concave, and forming the upper 
extremity of the lachrymal duct and fossa. 

An inferior ox facial convex portion. 

The internal surface forms part of the maxillary and frontal sinuses. 

Articulations, 4. 

Frontal, nasal, superior maxilla and malar. 

NASAL. 

The nasal bones are two in number, articulating with each other in 
the median line, and forming the bony framework of the nose. 

They are triangular in shape, with their base upward uniting with 
the frontal, the apex downward and pointed, foroiing the nasal pro- 
longation. 



22 EQUINE ANATOMY. 

It also shows an external and internal face \ an external and inter- 
nal border. 

The external face is convex from side to side and smooth. 

The internal face gives attachment to the ethmoid, and is covered 
with mucous membrane. 

The external border unites with the lachrymal, superior and inter- 
maxillaries, the internal with the opposite nasal. 

Articulations, 5. 

Frontal, lachrymal, superior maxillary, inter-maxillary and oppo- 
site, 

INFERIOR TURBINATED. 

These two scroll-shaped bones are attached to the superior maxilla 
and palate, and rolled from behind forward. It separates the middle 
from the inferior nasal meatus. 

Articulations, 2. 

Superior maxilla and palate. 

VOMER. 

The vomer is a single bone in the median facial line, forming part 
of the nasal septum, and attached above to the sphenoid by its upper 
extremity, which is divided into two narrow processes. Its lower ex- 
tremity is attached to the superior maxillary palate and pre-maxillary 
bones. Its two lateral faces are smooth and covered with mucous 
membrane. 

Articulations, 8. 

Sphenoid, ethmoid, two superior maxillary , two pre-maxillary and 
two palate. 

INFERIOR MAXILLA. 

The lower jaw is a large bone forming the inferior and anterior part 
of the face, and articulating with the two temporal bones. It is 
convex externally, concave internally, forming the inter-maxillary 
space. It consists of two extre??iities, an inferior and superior, two 
faces, external and internal, and two borders, a superior and inferior. 

The inferior extre?nity shows — 

The union of the two lateral halves of the bone. 

An inferior or labial face, smooth and convex, containing the open- 
ing of the mental foramen on the sides ; at this point it is constricted, 
the neck. 



OSTEOLOGY. 23 

A superior or concave buccal face, supporting the tongue. 

A circumference, convex anteriorly, with sockets for the six incisors, 
and behind these for the two tusks. 

The space between the lateral incisors and tusks, is called the 
dental interspace or bars. 

The superior extremity shows — 

The condyloid process elongated transversely for articulation with 
the glenoid cavity of the temporal. 

The neck, a constriction below this. 

The coronoid process, in front of the condyle, separated from it by 
the sigmoid notch, is flattened on its sides, and receives the insertion 
of the temporal muscle. 

The external face shows — 

A smooth surface below a rough one above, for the masseter. 

The internal face shows — 

In its upper one-third the entrance of the inferior maxillo-dental 
canal, which runs down under the teeth, giving off another, the mental 
foramen (see above), and then continued in the bone under the in- 
cisors. 

A smooth surface in its lower two-thirds. 

The mylo-hyoid ridge, a line running parallel with and below the 
teeth. 

The \ genial surface, a rough spot at the junction of the two sides. 

The anterior border shows — 

The alveolar surface, already described, and a thin portion for 
muscular insertion. 

The posterior border shows — 

A sharp, straight portio7i and a more rounded portion above, 
changing its direction at this point. It is there called the angle. 

Articulartions, 2. 
The temporals. 

THE FOSS.E. 

The cranial cavity is oval in form, the walls formed by the frontal, 
parietals and occipital above ; the occipital, parietals, temporals and 
sphenoid on the sides ; the occipital basilar process, the sphenoidal 
body, the transverse portion of the ethmoid, and internal surface of 
the frontal below. 

It is divided into a?iterior or cerebral and posterior or cerebellar 



24 EQUINE ANATOMY. 

fossae by the petrous portion of the temporal. In the posterior fossa 
is the foramen magnum, the communication between the spinal and 
cerebral cavities. 

Contents — cerebrum, cerebellum, cranial nerves and vessels. 

The orbital cavity and nasal fossce are described with the special 
senses of sight and smell. 

The temporal fossa?, oval in shape, lie behind the orbit, on the outer 
cranial wall, bounded within by the parietal ridge, without by the 
zygomatic process. 

They lodge the temporal muscle, coronoid process and vessels. 

THE HYOID. 

The hyoid bone consists of seven segments, lying below the head, 
above the larynx and under the tongue, in the intermaxillary space 

It consists of a body, two thyroid or great cornua, two styloid or 
lesser cornua, and two styloid bones. 

The body is convex in front, concave behind, with two lateral pro- 
longations, continuous with the thyroid cornua, and an anterior appen- 
dix, projecting into the muscular structure of the tongue. 

The thyroid or great cornua project backward, articulating with 
the extremities of the thyroid cartilage. 

The styloid or lesser cornua are small, and articulate below with the 
body at its junction with the great cornua. It often has a cartilaginous 
nodule at its inferior extremity, the styloid nucleus. 

The styloid bones are long, flattened on the sides, articulating above 
with the hyoideal pi-olongation of the temporal, below with the lesser 
cornua. They represent the styloid process and stylo-hyoid ligament 
of man. 

THE STERNUM. 

The sternum forms the inferior boundary of the thoracic cavity, 
showing on either side articulations for the first eight ribs. It shows 
an anterior extremity, the cervical prolo?igation, and a posterior, the 
abdominal prolongation or xiphoid appendix. 

It is flattened, laterally, in its anterior two-thirds, and from above 
downward in its posterior one-third. 

Articulations, 16. 

With eight anterior ribs on either side. 



OSTEOLOGY. 25 

THE RIBS. 

The ribs are 36 in number, 18 on either side, forming the lateral 
boundaries of the thorax, terminating below by cartilaginous prolon- 
gations, the costal cartilages. They articulate above with the dorsal 
vertebrae. They are divided into sternal or true, eight in number, 
and asternal or false \ the posterior ten. 

General Characteristics. — Each rib has an external convex and 
internal concave smooth surface and an anterior or convex border, 
a posterior border, showing a groove for the intercostal vessels and 
nerves, a shaft and two extremities. 

The superior extremity articulates with the vertebral column, and 
shows a head with two demi-facets for the bodies of the vertebrae in 
front and behind, a neck below the head, and a ttiberosity for articu- 
lation with a dorsal transverse process. 

The inferior extre7nity is excavated for the cartilage. 

The costal cartilages are flattened laterally, the first eight lying on 
the sternum, the remainder articulating with the cartilage in front. 

The length of the ribs increases from the 1st to the 9th, then de- 
creases ; their width from the 1st to the 6th, then decreases. 

The 1st rib has no outer groove and no notch on its head. Its 
cartilage is short and thick, and has an articular facet below for the 
opposite. 

The 18th rib has no external channel, and the facet on its tuberosity 
is confounded with that of its head. 

For thorax, see Lungs. 



THE ANTERIOR EXTREMITY. 

This is divided into the shoulder, arm, forearm and forefoot or 
hand. 

THE SHOULDER. 

In solipeds this consists of the scapula only, the clavicle being 
absent. 

THE SCAPULA. 

The scapula or shoulder blade is a flat, triangular bone, lying at the 
anterior and inferior part of the outer thoracic wall, articulating below 
with the head of the humerus. Its general direction is downward and 
forward. 

3 



26 EQUINE ANATOMY. 

It has two surfaces, external and internal, three angles, anterior 
or cervical, posterior or dorsal, and inferior or humeral, and three bor- 
ders, anterior, posterior, and superior. 

The external surface shows two cavities, giving attachment to the 
antea- and postea-spinati muscles, divided by a marked crest, the 
spine, running in its long axis ; elevated in its middle, the tuberosity. 

The internal surface is concave, forming the sub -scapular fossa for 
the muscle of the same name. 

The anterior or cervical angle is thin ; the posterior thick. 

The inferior or humeral angle has a constricted neck ; below this 
the glenoid cavity \ a round, shallow depression, for the humeral head. 

In front of the cavity is the coracoid process, with a base and a sum- 
mit curved inwardly. 

The superior border is prolonged by a well-marked, flattened carti- 
lage. 

The anterior border is sharp and thin ; the posterior, thicker and 
concave. 

It articulates with the humerus. 

THE ARM 

The single bone forming the arm is the humerus. 

THE HUMERUS. 

The humerus is a long bone, articulating above with the scapula, 
below with the ulna and radius. It has a shaft, an upper and a lower 
extremity. 

The shaft has — 

An anterior surface, showing below some muscular imprints. 

A posterior surface, smooth and rounded. 

An external surface, which shows a groove, winding from above 
downward, and behind forward, called the furrow of torsion, and is 
bounded in front by an anterior crest, behind by the posterior crest. 

The anterior crest ends below, at the junction of the upper and 
middle thirds, in the deltoid imprint, a rough and prominent eleva- 
tion, with a concavity toward the furrow of torsion. The furrow of 
torsion lodges the short flexor of the forearm. 

The internal surface is rounded, and has, at its middle, a rough 
depression for the teres major and latissimus dorsi. The nutrient 
foramen is at its lower third. 



OSTEOLOGY. 2J 

The superior extremity has — 

A convex head for articulation with the glenoid cavity. 

An external or great tuberosity, which shows a summit, crest and 
convexity. 

An internal or small tuberosity, receiving the insertion of the sub- 
scapulars. 

The bicipital groove, between the two tuberosities, and running 
downward. It consists of two grooves and a central elevation, which 
allow the passage of the fibro-cartilaginous tendon of the biceps. 

The inferior extremity has — 

A transversely elongated articular process, convex from before back- 
ward, and divided into two, a larger internal one, the trochlea, and a 
smaller external, the condyle; behind and above this a depression, 
which receives the beak of the olecranon in extension, called the 
olecranon fossa. In front and to the inner side, another, the coronoid 
fossa, which receives the coronoid in flexion. On the inner side, above 
the trochlea, the epi-Jrochlea, a bony elevation. On the outer side, in 
the same position, the epi-condyle. 

Articulations, 3. 

Scapula, radius and ulna. 

THE FOREARM. 

This consists of two bones, the radius and ulna, united into one 
at an early age. 

THE RADIUS. 

The radius is a long bone articulating above with the humerus, 
and below with the carpus. 

It shows — 

An external and internal border, thick and rounded. 

An a7iterior surface, smooth and convex. 

A posterior surface, concave, with a rough, triangular surface from 
the upper to the lower fourth, for attachment of the interosseous 
ligament ; above, a transverse groove, to form the radio-ulnar arch, a 
rough spot at its inferior third. 

The superior extremity shows — 

An articular stirface, smooth end concave, divided into a double 
depression externally, a middle ridge, and an internal depression. 

A well-marked external tuberosity. 



28 EQUINE ANATOMY. 

The internal or bicipital tuberosity, for attachment of the coraco- 
radialis. 

Below this, a transverse groove, for the short flexor of forearm. 

The coronoid process, a small projection anteriorly. 

Two facets, posteriorly, for the ulnar articulation. 

The inferior extremity shows — 

Below, the articulating surface for the four upper carpus. 

Two tubercles for ligaments, externally and internally. 

Thi'ee grooves anteriorly, the two outer ones lodging the anterior 
extensors of the phalanges and metacaipus ; the internal oblique one, 
the oblique exte7isor. 

A strongly marked ridge behind, for ligaments. 

Articulations, 6. 

Humerus, ulna, pisiform, cuneiform, semi-lunar and scaphoid. 

THE ULNA. 

The uhia is a long bone forming the posterior and upper three- 
fourths of the forearm, and strongly united to the radius. 

It has a shaft, an upper and lower extremity. 

The shaft is triangular, and has — 

An external smooth, internal concave, and an a7iterior rough sur- 
face. The latter shows two facets and the ulnar groove for the radio- 
ulnar arch. 

There are also two lateral, and a posterior rough, borders. 

The tipper extretnity shows — 

A superior enlargement, the olecranon process, for the attachment 
of the extensors of the forearm. This has external convex and in- 
ternal concave surfaces. 

Its anterior portion shows a deep notch, the sigmoid cavity, for 
articulation with the humerus, terminating above in the beak. 

The inferior extremity shows — 

A sinall knob, the capiteilum, which sometimes reaches to the end 
of the radius. 

Articulations, 2. 

The humerus and radius, 

THE FORE-FOOT^ OR HAND. 

This comprises in the horse the carpus, seven in number, three 
metacarpus, three phalanges and three sesamoids. 



OSTEOLOGY. 29 

THE CARPUS. 

The carpus, seven in number, are divided into a superior and an 
inferior row. 

The superior row are named from without inward — the (/) pisiform 
or super-carpal, (2) cuneiform, (j) semi-lunar, and (f) scaphoid. 

The inferior row are named — 

(7) Unciform, (2) os magnum and ( j) trapezoid. 

The (/) super-carpal has an external convex face, an internal con- 
cave face and a circumference, free except anteriorly, where it articu- 
lates with the radius and cuneiform. 

The (2) cuneiform is wedge-shaped, and articulates with the radius, 
super- carpal, semi-limar, and imciform. 

The (j) semi-lunar is half-moon -shaped and articulates with the 
cuneiform, scaphoid, radius, unciforin and magnum. 

The (^) scaphoid is boat-shaped and the largest of the row, articu- 
lating with the radius, semi-lunar, magnum and trapezoid. 

The unciform is hook-shaped and articulates with the cutieifonn, 
semi-lunar, magnum, external and middle metacarpals. 

The (.?) tfj magnum, the largest, articulates with the semi- lunar, 
scaphoid, imciform, trapezoid, internal and middle metacarpals. 

The (j) trapezoid, resembling the same geometrical figure, articu- 
lates with the scaphoid, magnum, middle and internal metacarpals. 

THE METACARPUS. 

This region consists of three portions, the middle or principal, and 
two lateral, the external and internal metacarpals. 

The principal metacarpal shows — 

A shaft, smooth and rounded in front, flattened behind, with articu- 
lar surfaces on each side for the rudimentary bones ; at its upper third 
the nutrient foramen. 

An upper extremity articulating with the inferior carpal row. 

An inferior extremity, showing two articular condyles, separated 
by a median ridge. On each side are ligamentous depressions. 

The rudiinentary metacarpals (or splint-bones) show a superior 
extremity articulating with the inferior carpal row, an inferior 
extremity extending as far as the lower fourth of the middle bone and 
ending in a button and a shaft with three surfaces, an anterior, articu- 
lating with the middle, external and internal smooth ones. 

The internal is the thicker and longer, and has two articular facets 
above. 



30 EQUINE ANATOMY. 

THE PHALANGES. 

THE FIRST PHALANX (OR PASTERN BONE). 

The first phalanx lies between the principal metacarpal and the 
second phalanx, and has a shaft and two extremities. 

The shaft has an anterior convex surface, a posterior, flattened and 
rough, and two thick borders. 

The upper extremity has two articular depressions, separated by a 
ridge. 

The inferior extremity has two condyles, separated by a groove and 
laterally two ligamentous depressions. 

SECOND PHALANX (OR OS CORON^). 

The second phalanx is a short bone with two articular depressions 
above, two articular processes below, an anterior face with imprints, 
and a posterior face with a transverse gliding surface. 

Articulations. 

First phalanx, third phalanx and navicular bone. 

THIRD PHALANX (OR OS PEDIS). 

The third phalanx supports the hoof and anterior limb. It is 
somewhat pyramidal in shape, and is divided into three faces, three 
angles, two lateral borders. 

The anterior face is perforated for vessels and shows laterally the 
pre-plantar fissure between the basilar and retrossal processes ; the 
patilobe eminence below the fissure. 

The superior face shows — 

Two articular cavities separated by a ridge, for the second phalanx. 

The inferior (or solar) face shows — 

A fiat surface below, on which the foot rests, a curved line, the 
semi-lunar crest, and laterally two channels, the plantar fissures, 
opening into a cavity in the interior, the semi-lunar sinus. 

The superior border has its convexity forward, and shows the 
pyramidal eminence for muscular insertion. 

The inferior border is convex and perforated by foramina. 

The posterior border shows a facet for the navicular bone. 

The lateral angles show two posterior projections, a superior, the 
basilar, and inferior, retrossal processes. Between the two is the 
origin of the pre-plantar fissure. 



OSTEOLOGY. 3 1 

THE SESAMOIDS. 
The sesamoids consist of two superior or large, and one inferior, 
small or navicular bone. 

THE LARGE SESAMOIDS. 

These are two in number, lying side by side behind the superior 
part of the first phalanx. Each one is pyramidal, and has an anterior 
face articulating with the metacarpal, a posterior, smooth for the 
gliding of tendons, a lateral face, a base and summit. 

They articulate with the metacarpal and first phalanx. 

THE NAVICULAR BONE. 

The small sesamoid bone lies behind the third phalanx, to which 
it is attached. It is long transversely and narrow, and shows a 
superior stirface, articulating with the second phalanx ; an anterior 
surface, articulating with the third phalanx ; an inferior surface, 3. 
posterior border and two extremities. 



THE POSTERIOR EXTREMITY. 
This is divided into the pelvis, thigh, leg, and foot. 

THE PELVIS. 

The pelvis is a bony cavity containing the sexual organs and 
termination of the intestinal tract. It is formed above by the sacrum 
laterally, and below by the os innoininata. 

The os innominata are two bones, each one composed of three 
segments closely fused together. In early life the innominate bones 
are separate, but they are completely joined as age advances. They 
consist of three segments, the ilium, ischium and pubcs. 

THE ILIUxM. 

The ilium is flat and triangular, and corresponds internally to the 
sides of the sacrum. It has two surfaces, three borders, and three 
angles. The external surface is rough, the internal surface shows an 
external smooth and internal rough portion, the auricular surface iox 
articulation with the ilium. The anterior border is rough, the ex- 



32 EQUINE ANATOMY. 

ternal thick and concave, the internal thin and concave, forming the 
great sciatic notch. 

The external angle, or anterior superior spinous process is thick, 
wide and flat, and called the angle of the haunch. The internal, or 
posterior superior spine, curving backward and upward, is called the 
angle of the croup. The posterior angle forms part of the cotyloid 
cavity ; above this cavity is the supra-cotyloid crest, two rough points 
for origin of the rectus, and ilio-pectineal eminence at the junction 
with the pubes. 

THE PUBIS. 

The pubis is flattened from above down, elongated transversely, 
and has two surfaces, three borders and three angles. It lies inside 
the ilium and in front of the ischium. 

The superior or pelvic surface forms the pelvic floor, and is smooth 
and concave. 

The inferior surface is rough and convex and shows a groove for 
the pubio-femoral ligament. 

The anterior border is rough, the internal is united with the oppo- 
site to form the symphysis, and the posterior forms the anterior bound- 
ary of the obturator foramen. 

The external or cotyloid angle forms the bottom of the cotyloid 
cavity. 

The internal unites with the opposite. 

The posterior is united with the ischium. 

THE ISCHIUM. 

The ischium lies behind the pubes and ilium, and is the smallest of 
the three portions. 

It has two surfaces, a superior or pelvic, smooth, and an inferior, 
rough, four borders and four angles. 

The anterior border bounds the obturator foramen, the posterior 
diverging forms the sciatic arch, and shows the ischiatic spine. 

The external is concave, forming the lesser sciatic notch. 

The internal unites with the opposite to form the ischial symphysis. 

The antero-external angle forms part of the cotyloid cavity ; the 
antero-internal unites with the pubis ; the postero-external forms 
an enlargement, the tuberosity ; the postero-internal unites with the 
opposite. 

The cotyloid cavity (or acetabuhun) is a deep excavation, at the 



OSTEOLOGY. 33 

junction of the three bones, with a narrow rim above, and incomplete 
below, where it communicates with the sub-pubic notch. It receives 
the femoral head. 

The obturator (or oval) foramen is composed of the pubis and 
ischium, and forms part of the lower pelvic boundary, when closed 
in by the external and internal obturator muscles. 

THE PELVIS. 

This cavity has an inlet bounded above by the sacrum, below by 
the pubes, laterally by the ilia. 

It has four diameters, a vertical, from the sacrum to the anterior 
pubic symphysis, of Sj4 inches, a horizontal, between the pectineal 
eminences, of 8^ inches, and two oblique, from the sacro-iliac joints 
to the pectineal eminences, of 8^ inches. 

It also has an outlet through which pass the rectum and genital 
organs, bounded above by the summit of the sacrum, below by the 
upper surface of the ischia, laterally by the sacro-ischiatic ligaments. 

It has two diameters, a vertical, of 6^ inches, from the sacrum to 
the ischium, and a transverse, of 7 T 7 <y inches, between the supra- 
cotyloid crests. 

The pelvis of the mare is much more roomy than that of the male, 
being more marked in its transverse diameters. 



THE THIGH. 
This consists of one bone, the femur. 

THE FEMUR. 

The femur lies between the pelvis above and the tibia below, having 
a general direction downward and forward. 

It has a shaft and upper and lower extremities. 

The shaft has — 

An external, anterior and internal face, all smooth and convex, 
and a posterior, rough and irregular. 

The posterior face shows in its upper one-third internally a rough 
elevation, the lesser or i?iternal trochanter, a rough surface for the 
attachment of the pectineus and adductor magnus, below a deep 
groove and a number of rough elevations, the supra-condyloid crest ; 
in its upper third rough lines and crests. 



34 EQUINE ANATOMY. 

The upper extremity shows — 

The head articulating with the acetabulum, forming two-thirds of a 
sphere and a constriction externally, the neck. 

The great or external trochanter \ outside and above, with a summit, 
convexity and crest. 

The digital ox trochanterian fossa, behind and below, receiving the 
obturator muscles. 

The inferior extremity is flattened laterally and shows — 

The external and internal condyles^ separated by a notch behind, 
with depressions for the crucial liga?nents. 

The trochlea, a wide, smooth surface between the condyles anteri- 
orly, on which the patella glides. 

A fossa for muscular insertion outside the preceding. 

Rough spots outside each condyle, for muscular and ligamentous 
insertion. 

Articulations, 3. 

Os innominata, patella and tibia. 



THE LEG. 
This consists of three bones, the tibia, fibula (or peroneus) and 
patella (or knee-pan). 

THE TIBIA. 

The tibia is a long bone. Its general direction is downward and 
backward, and has a shaft and upper and lower extremity. 

The shaft has three borders and three surfaces. 

The anterior border is sharp above, and known as the tibial crest. 

The external border is concave above, forming part of the tibial 
arch. The internal border is thick. 

The external surface is concave above, convex below, giving origin 
to the fleshy part of thefexor of the metatarsus. 

The internal surface presents above, muscular imprints for the 
adductors and semi-lendinosus. 

The posterior surface is divided, by an oblique line, into two por- 
tions the upper giving attachment to the popliteus, the lower to the 
perforans. 

The superior extremity shows — 

An anterior tuberosity, separated from the external by the groove for 



OSTEOLOGY. 35 

the tendon of the flexor of the metatarsus. It has a depression in 
front for the middle patellar ligament. 

The external tuberosity ', with a facet for the fibular head. 

The internal tuberosity, with ligamentous imprints. 

Above, two oval depressions for the condyles of the femur; the 
external is the wider. Between the two an eminence, the spine, for 
attachment of ligaments and cartilages. 

The inferior extrei7iity shows — 

An external tuberosity, with a vertical fissure for the lateral extensor 
of the phalanges. 

An internal tuberosity, with an oblique channel for the oblique flexor 
of phalanges. 

An articular surface for the astragalus, two antero-posterior depres- 
sions, separated by a median elevation. 

Articulations, 4. 

Femur, patella, fibula and astragalus. 

THE FIBULA OR PERONEUS. 

The fibula is a rudimentary bone lying outside the tibia and articu- 
lating with it alone. 

It has a superior and inferior extremity and shaft. 

The superior extremity is called the head, and shows internally an 
articular facet for the tibia, externally rough elevations for ligaments. 

The inferior extremity ends in a blunt point at the end of the upper 
third of the tibia. 

The shaft is, thin and small, forming the outer side of the tibial 
arch. 

THE PATELLA. 

The patella is a sesamoid bone, developed in the tendon of the 
triceps extensor and strongly attached to the tibia by three liga- 
ments. 

It has a superior face, rough, for attachment of the extensor cruris. 
An a?tterior, convex, and a. posterior, covered with cartilage and divided 
by a median ridge into an external and internal articular facet, the 
latter the larger, and both articulating with the femoral trochlea. 

Articulations, 2. 

Femur and tibia. 



36 EQUINE ANATOMY. 

THE FOOT. 
This is divided into the tarsus, metatarsus and bones of the digit. 

THE TARSUS. 

The tarsus corresponds to the carpus of the anterior foot, and con- 
sists of six or seven segments. 

These segments are divided into two rows : an upper and lower. 
In the former, in front, is the astragalus, behind the os calcis ; in the 
latter, outside, is the cuboid, inside, above, the scaphoid, below the 
large and small cuneiforms. There are sometimes three cuneiforms, 
making seven segments. 

THE ASTRAGALUS. 

The astragalus lies between the tibia above, the scaphoid below, 
and the calx behind. 

It has external and internal rough faces, a posterior with facets for 
the os calcis, an inferior convex for the articulation with the scaphoid 
and a superior and anterior with two articular elevations and a depres- 
sion for the tibial articular surface. 

Articulations, 4. 

Tibia, os calcis, scaphoid and cuboid, 

THE OS CALCIS OR CALCANEUS. 

The os calcis is elongated, lying behind the astragalus, above the 
cuboid, and forming the summit of the tarsus. It shows — 

A convex outer surface and concave inner, forming the tarsal arch. 

A concave anterior and thick posterior border. 

A superior exlre7nity with a rough spot for insertion of the gastroc- 
nemius, a smooth surface on which the tendon plays, and behind 
another for the gliding of the perforatus. 

The inferior extremity shows articular facets for the astragalus and 
cuboid. 

Articulations, 2. 

Astragalus and cuboid. v 

The cuboid is irregularly quadrilateral in shape, and articulates 
with the calcaneus, astragalus, scaphoid, middle and external meta- 
tarsals, and large cuneiform. 



ARTHROLOGY. 37 

The scaphoid is boat-shaped, articulating with four; the astragalus 
above, cuneiforms below, and the cuboid externally. 

The great cuneiform (wedge-shaped), lies inside the cuboid, articu- 
lating with it, the small cuneiform, scaphoid, middle and internal 
metatarsals. 

The small cuneiform lies on the inner side of the tarsus, articulating 
with the scaphoid, large cuneiform, 7niddle and internal metatarsals. 

THE METATARSUS. 

The median is longer and larger than that in the anterior extremity. 
The external is longer and thicker than the internal, which has two 
facets above for the tarsus. 

THE DIGITAL REGION. 

The first phalanx is shorter, the second narrower, the third nar- 
rower, more V-shaped, the sesamoids smaller, and the navicular 
shorter and narrower than the corresponding bones of the anterior foot. 



ARTHROLOGY. 

The articulations are divided into three classes : — 
i. Synarthroses or immovable joints. 

2. Amphiarthroses or limited in motion. 

3. Diarthroses, freely movable joints. 

Synarthroses are further divided into — 

(a) Schindylesis, a bony plate received into a groove. 

(b) Gomphosis, a conical process in a socket. 

(c) Sutura or by indentation, which are again divided into sutura 
vera and sutura notha. 

(d) Sutura vera, true sutures, 
Sutura dentata, tooth-like processes. 
S. serrata with saw-like processes. 

S. limbosa with beveled margins and dentated processes. 

(e) Sutura notha, false sutures. 

S. harmonia by opposed rough surfaces. 
S. squamosa with overlapping bony tables. 

Diarthroses are divided again into — 
Arthrodial, or gliding joints. 



38 EQUINE ANATOMY. 

Enarthrodial, or ball and socket. 

Gingly?nus, or hinge-like. 

Diarthrosis rotatoria, or a pivot which turns in a cavity. 

Condyloid, one or more condyles received in oval excavations. 

Examples. 

S. dentata. — Intra-parietal suture. 

S. serrata. — Inter-frontal suture. 

S. limbosa. — Fronto-parietal suture. ■ 

S. harmonia. — Occipito-temporal suture. 

S. squamosa. — Parieto-temporal suture. 

Amphiarthroses. — Bodies of vertebrae, sacro-iliac joints. 

ArthrodiaL — Carpo-metacarpal joints. 

Enarthrodial. — Hip and shoulder joints. 

Ginglymus'— Hock and humero-radial joints. 

Diarthrosis rotatoria. — Atlo-axoid joint. 

Condyloid. — Temporo-maxillary and knee joints. 

Structures entering into joints are — 

Articular lamellae of bone, ligaments, cartilage, fibro-cartilage, syno- 
vial membrane and synovia. 

Movements of joints are — 

Flexion, extension, abduction, adduction, external rotation, internal 
rotation, circumduction and gliding. 

Articulations of vertebral column — 

i . Common superior vertebral ligament, lies above bodies of verte- 
brae, and attached to them from the axis to the sacrum. 

2. Common inferior vertebral ligament, lies below bodies, and at- 
tached to them from sixth or eighth dorsal to sacrum. 

3. Inter articular fibro-cartilage t between the bodies of the vertebrae, 
except between atlas and axis. 

4. Capsular, between articular processes. 

5. Inter- transverse, between transverse processes. 

6. Inter-lamellar, between laminae. 

7. Inter-spi?ious, between spinous processes. 

8. Supraspinous, between tips of spinous processes. 
Ligame7itum nucha is the continuation of the supra-spinous liga- 
ment from the first dorsal to the occiput ; it supports the head. 

In the sacral and coccygeal regions the articulations are more or less 
fused or rudimentary. 



ARTHROLOGY. 39 

In the sacro-lumbar articulation the interarticular fibro-cartilage is 
very thick, and the transverse process of the last lumbar articulates 
with the external angles of sacrum. 

The fifth and sixth lumbar also articulate between their transverse 
processes. 

The movements of the spine are — 

Flexion, extension and lateral motion, free in the cervical but re- 
stricted in the other regions. 

ATLO-AXOID ARTICULATION. 

Odontoid and articular processes of axis to corresponding depres- 
sions on atlas. 

Ligaments. 

Odontoid, from odontoid to inferior arch of atlas. 

Superior atlo-axoid, between spines. 

Inferior atlo-axoid, below bodies. 

Capsular ligaments (two), between articular processes. 

Action. 

Lateral rotation. 

OCCIPITO-ATLOID. 

Ligaments. 

Two capsular. 

Two lateral, from transverse process to occiput. 

Action. 

(Condyloid,) extension, flexion and lateral inclination. 

TEMPORO-MAXILLARY. 

{Double condyloid joint '.) 

Ligaments. 

Capsular, from margins of glenoid cavity to neck of condyle of 
inferior maxilla. 

biterarticular fibro-cartilage moulded on condyle. 

Two synovial membranes, one above, one below cartilage. 

Action. 

Depression, elevation, lateral motion and gliding. 



40 EQUINE ANATOMY. 

HYOID. 

Two elastic cartilages, between styloid bone and temporal. 
Two capsular ligaments, between body and lesser cornua. 

Motion. 

Amphiarthrodial. 

THORAX. 

COSTO-VERTEBRAL. 

Two convex facets on head of ribs and two depressions in vertebrae, 
in front and behind, also in the intervertebral substance. 

Ligaments. 

Interarticular, from head of rib to intervertebral disk, none in first, 
and sometimes not in second articulation. 

Inferior (stellate), of three fasciculi, running to vertebrae in front and 
behind and intervertebral substance. 

Two capsular ligaments, one in front and one behind the inter- 
articular ligament. 

COSTO-TRANSVERSE. 

Between facet on tuberosity of rib and dorsal transverse processes. 
Anterior costotransverse or interosseous. 
Posterior cos to-transverse. 
One synovial membrane. 

CHONDRO-STERNAL. 

Eight upper ribs, with sternum, by cartilages. 

Superior chondro-sternal. 

Inferior chondro-sternal. 

The articulations of the first two ribs run into each other. 

CHONDRO-COSTAL. 

Implantation of a cartilage, on the one in front, by means of 
diarthrodial facets. 

Their movements are obscure. 



ARTHROLOGY. _1I 

ANTERIOR LIMB. 

SCAPULOHUMERAL. 

Enarthrodial joint, between head of humerus and glenoid cavity 
of scapula. 

Ligaments. 

A rudimentary glenoid ligament, deepening the cavity. 
Capsular ligament, from margins of cavity to neck of humerus. 
Two supporting fasciculi from coracoid process to head of humerus. 
The muscles in relation to joint are — 

1. In front, coraco-radial. 

2. Behind, large extensor of forearm and teres minor. 

3. Outside, short abductor of arm and postea spinatus. 

4. Inside, subscapularis. 

Action. 

Abduction, adduction, flexion, extension, rotation and circumduction. 

HUMERORADIAL. 

Ginglymus, between inferior extremity of humerus and upper 
extremity of ulna and radius. 

Ligaments. 

Anterior, from humerus above articular surface to anterior part of 
radius. 

External lateral, from cavity outside of humerus to external portion 
of radius. 

Internal lateral, inner tuberosity of inferior extremity of humerus, 
to radial tuberosity and to interosseous fibres. 

Action. 

Flexion and extension. 

RADIO-ULNAR. 

Two facets and rough surfaces on each bone. 

Ligaments. 

Two interosseous, the lower always ossifies, the upper rarely. 
External peripheral band. 
Internal peripheral band. 

Action. 

Very little in youth, none when consolidated. 
4 



42 



EQUINE ANATOMY. 
Fig. 2. 




SCAPULOHUMERAL AND HUMERORADIAL ARTICULATIONS, WITH THE MUSCLES 
SURROUNDING THEM (EXTERNAL FACE). 

Scapulo-humeral capsular ligament ; 2, Short abductor muscle of the arm; 3, Its inser- 
tion in the humerus ; 4, Insertion of the subspinous muscle on the crest of the great 
tuberosity; 5, Coraco-radial muscle; 6, Its tendon of origin attached to the coracoid 
process; 7, Its radial insertion confounded with the anterior ligament of the ulnar arti- 
culation; 8,8, External lateral ligament of that articulation ; 9, Anterior ligament; 10, 
Anconeus, or small extensor of the forearm; 11, Origin of the external flexor muscle 
of the metacarpus; 12, Short flexor muscle of the forearm. — a, Tuberosity of the scapu- 
lar spine. — b, Superspinous fossa. — c, Subspinous fossa. — d, Convexity of the small tro- 
chanter. — e, Summit of the trochanter. 



ARTHROLOGY. 43 

RADIO-CARPAL. 

Lower articular surface of radius with four upper carpal bones. 

Ligaments. 

Internal, from radius to fourth bone. 

Superficial external, radius to supercarpal bone. 

Deep external, radius to second bone and interosseous ligament. 

Action. 

Imperfect ginglymus. 

CARPUS. 

First row with each other. 

Three anterior and three interosseous running in front of and 
between bones. 

Second row with each other. 
Two anterior and two interosseous. 
First and second rows with each other. 

Ligaments. 

External posterior, from first of upper to second bone of lower row. 

Internal posterior, from internal bone of upper row to second and 
third of metacarpal row. 

External, from supercarpal to first bone of second row and head of 
external metacarpal. 

Action. 

Imperfect ginglymus. 

CARPO-METACARPAL. 

Between three lower carpus and three metacarpus, forming a plani- 
form diarthrosis. 

Ligaments. 

Two anterior, one between second bone and principal metacarpal ; 
the other from the first to external metacarpal. 

Two interosseus, from articulations between metacarpus to inter- 
osseous ligaments of second row. 

COMMON CARPAL LIGAMENTS. 

i. Anterior, from radius to principal metacarpal. 
2. Posterior, posterior part of radial surface to carpus and principal 
metacarpal. 



44 EQUINE ANATOMY. 

3. External lateral, from outer side of radius to first bones of 
upper and lower rows and outer metacarpal bone. 

4. Internal lateral, from inner side of radius to principal and 
inner metacarpal as well as into carpus. 

METACARPOPHALANGEAL, 

Ginglymus joint between end of metacarpal bone and first phalanx 
with the two upper sesamoids. 

Ligaments. 

Inter-sesamoid, between two sesamoids. 

Lateral sesamoid, between sides of sesamoids and upper extremity 
of first phalanx. 

Inferior sesamoid, of three fasciculi, from posterior surface of first 
phalanx to sesamoids. 

External and i?iternal lateral, from metacarpal to sides of first 
phalanx. 

Anterior, between anterior surfaces of both bones. 

Posterior or suspensory ligament of the fetlock, from first and sec- 
ond bone of inferior carpal row and posterior face of principal meta- 
carpal to top of sesamoids, divides into two fasciculi which pass for- 
ward and are inserted into the anterior extensor of the phalanges. 

Movements. 

Flexion and extension. 

FIRST INTER-PHALANGEAL ARTICULATION. 

Imperfect ginglymus between first and second phalanges. 

Ligaments. 

Two lateral ligaments between sides of bones. 

One posterior ligament or glenoidal fibro-cartilage attached to the 
first and second phalanges by six bands. It increases the articular 
surface below and foims a sheath for the passage of the perforans 
tendon, being in relation to the perforates at its side. 

Movements. 

Flexion, extension and some lateral motion. 

SECOND INTER-PHALANGEAL ARTICULATION. 

Imperfect ginglymus, between second and third phalanges. 

Ligaments. 

Interosseous, between navicular and pedal bones. 



AKTHROLOGY. 4$ 

Two anterior lateral, from anterior surfaces. 
Two posterior lateral, from anterior surfaces. 

Movements. 

Same as preceding. 



POSTERIOR EXTREMITY. 

SACROILIAC. 

An amp/iiarl/trosis, between auricular surface of sacrum and side 
of ilium. 

Ligaments. 

Sacro-iliac, about margins of articulation. 

Superior ilio-saeral, from internal angle of ilium to sacral spine. 

Inferior ilio-saeral, with preceding and inserted into sides of sacrum. 

Movements. 

Slight gliding. 

Saero-iliac ligament, from sides of sacrum by its superior border 
into super-cotyloid crest and ischial border by its inferior border, form- 
ing, with the lesser sciatie notch, the opening by which the internal 
obturator and pyramidal muscles leave the pelvis. 

An anterior border forms the greater sciatic forame?i with the notch, 
and through it pass the gluteal and sciatic vessels and nerves. 

A posterior border which embraces the semimembranosus muscle. 

ISCHIO-PUBIC SYMPHYSIS. 

In young animal is a true amphiarthrosis. 
In adult life bones are fused together. 

COXO-FEMORAL OR HIP JOINT. 

An enarthrodia between the cotyloid cavity and the head of the 
femur. 

Ligaments. 

Capsular, from margins of cotyloid cavity to neck of femur. 

Transverse, converting notch into a foramen. 

Cotyloid, deepening the cavity. 

Coxo-femoral (ligamentum teres) from bottom of cotyloid cavity to 
a depression in head of femur. 



4 6 



EQUINE ANATOMY. 



Pubo-femoral, from inferior face of pelvis, to be inserted with the 
preceding. 

Synovial membrane, very extensive. 



Fig. 3. 




SACROILIAC AND COXO-FEMORAL ARTICULATIONS, WITH THE SMALL DEEP MUSCLES 
SURROUNDING THE LATTER. 

Sacro-iliac ligament ; 2, Sacro-ischiatic ligament; 3, Great ischiatic notch; 4, Anterior 
portion of the capsular ligament of the coxo-femoral articulation ; 5, Internal band of 
cotyloid ligament; 6, Coxo-femoral ligament ; 7, Pubio-femoral ligament; 8, Its inser- 
tion into the femur; 9, Small gluteal muscle; 10, Origin of the straight anterior muscle 
of the thigh (rectus) ; 11, Anterior thin muscle (rectus parvus); 12, Pyramidal muscle 
of the pelvis; 13, External obturator muscle; 14, Square crural muscle (quadratus 
femoris); 15, Inferior sacro-coccygeal muscle. 



Muscles in relation to joint : — 
In front. — Gracilis and rectus. 
Behind. — Gemelli, internal obturator and pyramidalis. 



ARTHROLOGY. 47 

Below. — Ext. obturator. 
Above. — Small gluteal. 

Action. 

Same as shoulder. 

FEMORO-TIBIAL ARTICULATION. 

A condyloid joint between the femur above, tibia below and patella 

in front. 

Fig. 4. 




No. 2. External face: the external condyle of the femur and the meniscus have been re- 
moved to show the crucial ligaments. — 1, Anterior crucial ligament; 2, Posterior ditto; 
3, Fibular insertion of the external lateral ligament ; 4, Anterior patellar ligaments. — 
A, Internal meniscus; b, Anterior insertion of the external meniscus; c, Passage for 
the tendinous cord common to the flexor of the metatarsus and the anterior extensor 
of the phalanges ; d, Anterior and superior tuberosity of the tibia ; e, Tibial crest. 

Ligaments. 

Anterior or ligamentum patellce of three strong fasciculi from patella 
to the anterior surface of the tibia. 

Ante-patellar aponeurosis, an expansion of the fascia lata binding 
patella to the femur by two lateral fasciculi. 

External lateral, from external condyle to head of fibula. 

Internal lateral, from internal condyle to inner tibial tuberosity. 



48 EQUINE ANATOMY. 

Posterior, from posterior face of femur to tibia. In relation to 
external gastrocnemius and popliteal artery. 

Crucial. 

(a) Anterior or external, from front of tibial spine to inner side of 
external condyle. 

{U) Posterior or internal, in opposite direction. 

Interarticular fibro-cartilages (or menisci), (a) right and (b) left 
attached to tibial spine, and by fasciculi to femur and tibia. 

Synovial membrane. 

(a) Middle portion under patella. 

(p) Lateral portions under lateral ligaments.* 

Action. 

Flexion, extension and rotation on menisci. 

TIBIOFIBULAR ARTICULATION. 

A planiform diarthrosis, between tibia and fibula. 

Ligaments. 

Two lateral fasciculi, from sides of fibula to tibia. 

Interosseous, between two bones, leaving a space called tibio-fibular 
arch. 

Action. 

Limited. 

HOCK OR TARSAL ARTICULATION. 

Tibio-tarsal. 

A ginglymus, between lower end of tibia and astragalus. 

Ligaments. 

Anterior. — From front of tibia to astragalus, scaphoid, great cunei- 
form bones and astragalo-metatarsal ligament. 

Internal lateral. 

(a) Superficial fasciculus, from inner extremity of tibia to sides of 
tarsus and metatarsus. 

(b) Middle fasciculus. 

Tibial tuberosity to astragalus and calx. 

(c) Deep fasciculus. 
From tibia to astragalus. 
External lateral. 

(a) Superficial portion, from tibia to sides of tarsus and metatarsus. 

(b) Deep portion, from tibia to astragalus and calx. 



ARTHROLOGV. 49 

Action. 

Flexion and extension. 

Calcaneo-astragaloid. 

A compound diarthrodia between three or four facets on astragalus, 
with same on calx. 

Ligaments. 

Superior, external lateral, internal lateral and interosseous, running 
from one bone to another, as their names imply. 

Action. — Very limited. 

Second row of tarsus with each other. Between scaphoid, cuboid 
and two cuneiforms. 

Ligaments. 

Two anterior, the cuboido-cunean and ctcboido-scaphoid and two 
corresponding interosseous. 

An i?iterosseous scaphoid-cunean and inter-cunean. 

Action. — Very limited. 

Two rows of tarsus with each other. 

Ligaments. 

Two lateral ligaments of tibio-tarsal joint. 

Calcaneo-metatarsal, from posterior border of calx to cuboid and 
head of external metatarsal. 

Astragalo-melatarsal, from inner side of astragalus to scaphoid, 
great cuneiform and middle metatarsal. 

Posterior tarso-metatarsal from all of tarsus to top of metatarsus. 

One interosseous, between four bones. 

Action. — Very limited. 

Tarso-metatarsal. 

Between cubojd and cuneiform above, and metatarsal below. 

Ligaments. 

Those previously described and one strong interosseous. 
Synovial sacs of tarsus. 

1. Membrane of tibio-tarsal articulation, communicates in front with 
that between the two rows, and behind with the superior articulation 
of astragalus with calx. 

2. One for articulation, between scaphoid and great cuneiform, and 
also to the cuboido-scaphoid and posterior cuboido-cunean. 



50 EQUINE ANATOMY. 

3. That between two rows, which has communications as above, 
and with anterior cuboido-scaphoid joint. 

4. That of tarso-metatarsal articulation which ascends into anterior 
cuboido-cunean joint between cuneiform and down into inter-meta- 
tarsal articulation. 



MYOLOGY. 

THE MUSCLES. 

The muscles are the active portions of the locomotory apparatus, and 
form one-half of the body's weight. 

They are divided into striated or striped and unstriated or un~ 
striped. The former are voluntary the latter involuntary. 

The striped muscles consist of fibres divided into fibrillar, the whole 
being surrounded by a membrane, the perimysium. The fibrillar are 
composed of small portions, the sarcous elements, attached to each 
other end to end. Between the fibrillae is more or less interstitial 
substance. 

The unstriped muscles are found in the viscera as the intestine, and 
consist of fusiform cells, each with a distinct nucleus and bound 
together by connective tissue. 

Appendages of Muscles. 

These are tendo7is,fascice and aponeuroses. 

Tendo7is are round or flattened, white cords at the terminations of 
muscles, composed of condensed white fibrous tissue. 

Aponeuroses are flattened bands connected with, or the terminations 
of, the broad muscles, and composed of white fibrous tissue. 

Fascice are strong processes of the same structure, forming sheaths 
and coverings for the muscles. 

Bursce are thin bags filled with mucous or serous rluid, and placed 
on bony points over which muscles glide. Their office is to prevent 
friction. 

Sheaths of tendojis are composed of fibrous tissue, forming de- 
pressions or compartments in which tendons glide. When com- 
plete they are called vaginal. They may be lined with synovial 
membraiie. 



MYOLOGY. 51 

MUSCLES OF FACE. 

ORBICULARIS ORIS. 

Origin. — No bone attachment ; confounded with buccinator and 
other muscles in vicinity. 

Insertion. — About oral orifice. 
Action. — To close oral orifice. 
Nerve. — Facial. 

BUCCINATOR. 

Origin. — Maxillary tuberosity, above posterior three molar teeth of 
superior maxilla and from inferior maxilla, behind last molar. 
Insertion. — Into orbicularis. 
Action. — Compresses cheeks. 
Nerve. — Buccal, from fifth. 

ZYGOMATICO-LABIALIS. 

Origin. — From outer surface of masseteric fascia. 
Insertion. — On surface of buccinator. 
Action. — Retraction of lips. 
Nerve. — Facial. 

LACHRYMO-LABIAL. 

Origin. — Outer surface of lachrymal and malar bones. 
Insertion. — Into buccinator fascia. 
Action. — To corrugate skin of lower lid. 
Nerve. — Facial. 

SUPER-XASO-LABIALIS. 

{Levator labii snperioris et alcequce nasi of man.) 

Origin. — Frontal and nasal bones. 

Insertion. — Anterior division into external wing of nose and bucci- 
nator, posterior into angle of lips ; between divisions passes the 
super-maxillo-labialis magnus. 

Action. — Raises wing of nose and upper lip. 

Nerve. — Facial. 

SUPER-MAXILLO-LABIALIS. 

Origin. — Outer surface of super-maxillary and malar bones. 
Insertion. — With opposite into fascia of upper lip. 
Action. — Raises upper lip, or singly, carries it to one side. 
Nerve. — Facial. 



52 



EQUINE ANATOMY. 



SUPER-MAXILLO-NASALIS MAGNUS. 

Origin. — Below ridge on superior maxilla. 
Insertion. — Skin of external wing of nostril. 
Action. — Dilates anterior nares. 
Nerve. — Facial. 

Fig. 5. 




SUPERFICIAL MUSCLES OF THE FACE AND HEAD. 

i, Temporo-auricularis externus, or attollens maximus ; 2, Levator palpebral, or corrugator 
supercilii ; 3, Temporo-auricularis internus, or attollens posterior; 4,5, Zygomatico- 
auricularis, or attollens anterior; 6, Orbicularis palpebrarum ; 7, Parotido-auricularis, 
or deprimens aurem ; 8, Parotid gland; 9, Temporal, or sub-zygomatic vein ; 10, Ditto, 
artery; 11, 12, Superior and inferior maxillary nerves; 13, Fascia of the masseter 
muscle ; 14, Nasal bones ; 15, Super-naso-labialis, or levator labii superioris alaeq'ie nasi ; 
16, Super-rraxillo-labialis, or nasalis longus labii superioris; 17, External maxillary or 
facial artery«| 18, Facial vein ; 19, Super-maxillo-nasalis magnus, or dilatator naris 
lateralis ; 20, Superior maxillary nerve ; 21, Zygomatico-labialis, or zygomaticus ; 
22, Parotid, or Steno's duct; 23, Masseter; 24, Alveolo-labialis, or buccinator; 
25, Super-maxillo-nasalis parvus, or nasalis brevis labii superioris ; 27, Labialis, or 
orbicularis oris; 28, Maxillo-labialis, or depressor labii inferioris ; 29, Mento-labialis, or 
levator menti. 



SUPER-MAXILLO-NASALIS MINOR. 

Origin. — External process of pre-maxilla and superior maxilla. 
Insertion. — Skin and cartilage of nostril. 
Action. — Dilatation of nostril. 
Nerve. — Facial. 



MYOLOGY. 53 

TRANSVERSALIS NASI. 

Runs from one internal ala of nose to the other. 
Action. — To dilate nostrils. 
Nerve. — Facial. 

ANTERIOR INTERMEDIATE. 

Origin. — Facial surface of pre-maxilla above incisors. 

Insertion. — With maxilio-nasalis minor into inferior turbinated bone. 

Action. — Dilation of anterior nasal entrance. 

Nerve. — Facial. 

MAXILLO-LABIALIS. 

Origin. — Inferior maxilla behind last molar. 

Insertion. — Skin of lower lip. 

Action. — Depresses lower lip, or singly moves it laterally. 

Nerve. — Facial. 

POSTERIOR INTERMEDIATE. 

Origin. — Outer surface of inferior maxilla beneath incisors. 
Insertion. — Into fibres of orbicularis oris. 
Action. — Elevates lower lip. 
Nerve. — Facial. 

MASSETER. 

Origin. — Zygomatic process of temporal. 
Insertion. — Outer surface of ramus of jaw. 
Action. — Elevator of jaw. 
Nerve. — Inferior maxillary of fifth. 

TEMPORAL. 

Origin. — From temporal fossa, temporal fascia and outer border 
of orbit. 

Insertion. — Coronoid process and ramus of inferior maxilla. 
Nerve. — Buccal branch of fifth. 

EXTERNAL PTERYGOID. 

Origin. — Under surface of sphenoid and pterygoid process. 
Insertion. — Neck of condyle of maxilla. 

Action. — To pull inferior maxilla forward, alone to cause lateral 
motion, as in grinding food. 

Nerve. — Buccal branch of fifth. 



54 EQUINE ANATOMY. 

INTERNAL PTERYGOID. 

Origin. — Palatine crest and pterygoid process 
Insertion. — In hollow of maxillary ramus. 
Action. — Elevates and moves - j aw laterally. 
Nerve. — Inferior maxillary of fifth. 

DIGASTRIC. 

Origin. — Posterior belly from styloid process of occipital bone ; 
tendon passes through fibrous ring of insertion of stylo-hyoideus into 
hyoid. 

Insertion. — Into posterior border and internal face of inferior max- 
illa. 

Action. — Raises hyoid bone or depresses lower jaw. 

Nerve. — Facial. 

MYLO-HYOID. 

Origin. — Mylo-hyoid ridge of inferior maxilla. 

Insertion. — Body of hyoid and anterior appendix and median raphe 
between two muscles. 

Action. — Same as above and also elevates tongue. 
Nerve. — Inferior maxillary of fifth. 

GENIO-HYOID. 

Origin. — Genial surface of inferior maxilla. 
Insertion. — Extremity of hyoideal appendix. 
Action. — Draws hyoid forward and upward. 
Nerve. — Hypoglossal. 

STYLO-HYOID. 

Origin. — Superior angle of styloid bone. 

Insertion. — Base of hyoideal cornua. 

Action. — Antagonizes former ; carries hyoid up and back. 

Nerve. — Facial. 

KERATO-HYOID. 

Origin. — Posterior border of styloid cornu and inferior extremity of 
hyoid bone. 

Insertion. — Superior border of thyroid cornua. 
Action. — Approximates two cornua. 
Nerve. — Hypo-glossal. 



MYOLOGY. 55 

OCCIPITO-STYLOID. 

Origin. — Styloid process of occipital. 

Insertion. — Horizontal portion of posterior border of the styloid bone. 

Action. — Depresses inferior extremity of hyoid. 

Nerve. — Facial. 

TRAXSYERSUS HYOIDEI. 

Runs between superior extremities of styloid cornua. 
Action. — Approximates styloid cornua. 
Nerve. — H y po-glossal . 

TONGUE. 

STYLO-GLOSSUS. 

Origin. — Outer surface of lower extremity of styloid bone. 
Insertion. — Side and tip of tongue. 

Action. — Pulls tongue up and backward or to one side alone. 
Nerve. — Hypo-glossal. 

HYO-GLOSSUS MAXIMUS. 

Origin. — Side of appendix, body and great cornua of hyoid. 

Insertion, — Lateral borders of tongue. 

Actum. — Retracts tongue and depresses its base. 

GEXIO-GLOSSUS. 

Origin. — Posterior surface of body of lower jaw, near symphysis. 
Insertion. — Under surface of tongue. 
Action. — Pulls tongue forward or depresses it. 
Nerve. — Hypo-glossal. 

HYO-GLOSSUS MINIMUS. 

Origin. — Body of hyoid near small branch. 
Insertio)i. — Into base of tongue. 
Actio7i. — Contracts and retracts tongue. 



PALATE. 

PALATO-GLOSSUS. 

Origin. — From lateral wall of pharynx. 

Insertion. — Into side of tongue between hyo- and genio-glossi. 

Action. — EleYates tongue. 

Nerve. — Superior maxillary division of fifth and Meckel's ganglion. 



56 EQUINE ANATOMY. 

PALATO-PHARYNGEUS. 

-Origin. — From soft palate. 

Insertion. — Side of pharynx and superior border of thyroid cartilage. 

Action. — Makes tense and elevates free border of palate. 

Nerve. — Superior maxillary division of fifth and Meckel's ganglion. 

PALATO-STAPHYLEUS. 

Origin. — Uvular aponeurosis with opposite. 
Insertion. — Into free border of soft palate. 
Action. — Pulls palate upward and forward. 
Nerve. — Posterior palatine. 

PERI-STAPHYLEUS EXTERNUS (TENSOR PALATl). 

Origin. — Styloid process of temporal. 

Insertion. — Winds around pterygoid trochlea, changes its direction 
and spreads out into soft palate. 
Action. — Tensor of soft palate. 
Nerve. — Posterior palatine. 

PERI-STAPHYLEUS INTERNUS (LEVATOR PALATl). 

Origin. — With preceding. 

Insertion.*— Into palato-pharyngeus and soft palate. 

Action. — Elevator of soft palate. 

Nerve. — Posterior palatine. 



PHARYNX. 
Palato-Pharyngeus. — See above. 

PTERYGO-PHARYNGEUS (SUPERIOR CONSTRICTOR). 

Origin. — Pterygoid process. 

Insertion. — Into median raphe, with opposite, and hyoid and thyroid 
cartilage. 

Action. — Constricts pharynx and raises larynx. 

HYO-PHARYNGEUS (FIRST MIDDLE CONSTRICTOR). 

Origin. — Cornua of hyoid. 
Insertion. — Median raphe. 



s; 



MYOLOGY. 
THYRO-PHARYNGEUS (SECOND MIDDLE CONSTRICTOR). 

Origin. — External surface of thyroid cartilage. 
Insertion. — Median raphe. 

CRICO-PHARYNGEUS (INFERIOR CONSTRICTOR). 

Origin. — Superficial face of cricoid. 

Insertion. — Median raphe. 

Action. — With three above, as constrictors of pharynx. 

Nerves. — Glossopharyngeal, pneumogastric, sympathetic. 

STYLO-PHARYNGEUS. 

Origin. — Great thyroideal cornua. 
Insertion. — Sides of pharynx. 
Action. — Elevates and dilates pharynx. 
Nerves. — Same as preceding. 



TRUNK. , 

FLESHY PANNICULUS. 

Origin. — From flank to posterior border of olecranian mass of 
muscles and pectoralis major. 

Insertion. — One layer to anterior limb and one to small trochanter. 
Nerve. — Subcutaneous thoracic. 

CERVICAL REGION. — RHOMBOIDEUS. 

Origin. — First, fourth or fifth division vertebrae by spinous processes. 

Insertion. — Scapular cartilage. 

Action. — Draws shoulder upward and forward. 

Nerve. — Sixth cervical. 

LEVATOR ANGULI SCAPUL/E. 

Origin. — Transverse processes of last five cervical vertebrae. 
Insertion. — Anterior triangular surface in inner face of scapula. 
Action. — Draws scapula forward and upward. If scapula is fixed, 
inclines neck to side. 
Nerve. — Sixth cervical. 

SPLENIUS. 

Origin. — To lip of cervical ligament and first dorsal vertebrae. 
Insertion. — Into mastoid crest with small complexus, transverse 
processes of atlas and third, fourth and fifth cervical vertebrae. 

5 



58* EQUINE ANATOMY. 

Action. — Extends head and neck or draws them to side. 
Nerve. — Superficial cervical. 

GREAT COM PLEXUS. 

Origin ; Anterior Portion. — Transverse processes of first and second 
dorsal vertebrae, and articular tubercles of cervical vertebrae. 

Posterior Portion. — From spinous processes of first dorsal, and 
transverse processes of first four or five dorsal vertebrae. 

Insertion. — Occipital tuberosity. 

Action. — Extensor of head. 

Nerve. — Deep cervical. 

SMALL COMPLEXUS. 

Origin. — Same as anterior portion of former. 
Insertion, — Mastoid process of temporal. 
Action. — Extends head and inclines it to one side. 
Nerve. — Deep cervical. 

TRANSVERSE SPINOUS OF NECK. 

Origin. — To five last articular tubercles of cervical spine. 
Insertion. — Second, third, fourth, fifth and sixth cervical spinous 
processes. 
Action. — Extensor and flexor of cervical region. 
Nerve. — Deep cervical. 

% - INTER-TRANSVERSE OF NECK. 

Origin. — Six short muscles between transverse processes of cervical 
spine, except between first and second. 
Action. — Incline neck to same side. 
Nerve. — Superficial cervical. 

GREAT OBLIQUE OF HEAD. 

Origin. — Spinous process of axis. 
Insertion. — Transverse process of atlas. 
Action. — Rotates atlas on odontoid process. 
Nerve. — Second cervical. 

SMALL OBLIQUE. 

Origin. — Transverse process of atlas. 

Insertion. — Styloid process, external surface of occipital and mastoid 
crest. 



MYOLOGY. CQ 

Action. — Inclines head on atlas. 
Nerve. — First cervical. 

POSTERIOR GREAT STRAIGHT OF HEAD. 

Origin. — Spinous process of axis. 
Insertion.- — To occipital behind complexus. 
Action. — Extends head. 
Nerve. — Deep cervical. 

POSTERIOR SMALL STRAIGHT OF HEAD. 

Origin. — From superior face of atlas. 
Insertion. — Below preceding, on occipital. 
Action, — Same as preceding. 
Nerve. — Deep cervical. 

INFERIOR CERVICAL REGION. — SUBCUTANEOUS OF NECK. 

Origin. — Anterior prolongation of sternum and muscles of chest. 
Insertion. — Skin of neck — raphe — muscles of face, and zyomatic 
crest. 

Action. — Braces muscles and pulls mouth backward. 
Nerve. — Facial. 

MASTOIDO-HUMERALIS. 

Origin; Anterior Portion. — Mastoid process and crest. 
Insertion. — Furrow of torsion of humerus below deltoid imprint. 
Origin ; Posterior Portion. — Transverse processes of first four cer- 
vical vertebrae. 

Insertion. — With first portion. 

Action. — Carries limb forward or inclines head to side. 

Nerve. — Spinal accessory. 

STERNO-MAXILLARIS. 

Origin. — Cariniform process of sternum. 
Insertion. — Posterior border of inferior maxilla. 
Action. — Flexes head or turns it to one side. 
Nerve. — Spinal accessory. 

STERNO- HYOID. 

Origin. — Cariniform cartilage of sternum. 
Insertion. — Inferior surface of body of hyoid. 
Action. — Depresses hyoid and larynx. 
Nerve. — First cervical. 



6o 

9 



EQUINE ANATOMY. 
STERNO-THYROID. 

Origin. — As preceding. 

Insertio7i. — Posterior border of thyroid cartilage. 

Action. — As preceding. 

Nerve. — First cervical. 

Fig. 6. 




LATERAL VIEW OF THE NECK; MIDDLE LAYER OF MUSCLES. 

i, Funicular portion of the cervical ligament ; 2, Complexus major; 3, Complexus minor, 
4, Rectus capitis posticus major; 5, Rectus capitis posticus minor; 6, Stylo-maxillaris ; 
7, Carotid artery; 8, Pneumogastric nerve and branch of sympathetic; 9, Longus colli ; 
10, Recurrent nerve; 11, Inferior scalenus; 12. Spinalis, or transversalis colli ; 13, In- 
cision through rhomboideus and trapezius ; 14, Trachea. 



OMOHYOID. 

Origin. — Inner surface of sub-scapularis. 

Insertion. — Body of hyoid bone with sterno-hyoid (separates carotid 
artery from jugular vein in upper half of neck). 
Action. — Depresses hyoid. 
Nerve. — First cervical. 



MYOLOGY. 6 1 

RECTI'S CAPITIS ANTICUS MAJOR. 

Origi7i. — Transverse processes of third, fourth and fifth cervical 
vertebrae. 

Insertion. — Body and basilar process of sphenoid. 
Action. — Flexes head or carries it to one side. 
Nerve. — First cervical. 

RECTUS CAPITIS ANTICUS MINOR. 

Origin. — Inferior surface of atlas. 

Insertio?i, action, nerve. — Same as preceding. 

RECTUS CAPITIS LATERALIS. 

Origin. — From atlas outside preceding. 
Insertion. — Styloid process of occipital. 
Action. — Depresses head laterally. 
Nerve. — First cervical. 

SCALENUS SUPERIOR. 

Origin. — Transverse processes of last three or four cervical vertebrae. 
Insertion. — Superior extremity of first rib. 
Action. — Flexes neck, inclines it to one side, or raises rib. 
Nerve. — Third and fourth cervical. 

SCALENUS INFERIOR. 

Origin. — Transverse processes of last four cervical vertebrae. 
Insertion. — Anterior border and external face of first rib. 
Action. — As preceding. 
Nerve. — Third and fourth cervical. 

LONGUS COLLI. 

Origin ; Posterior Portion. — Inferior face of bodies of first six dorsal 
vertebrae. 

Insertion. — Inferior tubercle of sixth cervical vertebrae. 

Origin ; Middle Portion. — Transverse processes of last six cervical 
vertebrae. 

Insertion. — Inferior ridge of bodies of first six cervical vertebrae. 

Origin; Anterior Portion. — Anterior three or four fasciculi of 
middle portion. 



62 EQUINE ANATOMY. 

Insertion. — Inferior tubercle of atlas. 
Action. — Whole muscle flexes neck. 
Nerve. — Third and fourth cervical. 



REGION OF BACK. 

TRAPEZIUS. 

Origin. — Cervical cord and transverse processes of first dorsal 
vertebrae. 

Insertion. — Olecranian spine and scapular aponeurosis. 
Action. — Raises shoulder and carries it forward or backward. 
Nerve. — Spinal accessory. 

LAT1SSIMUS DORSI. 

Origin. — Spinous processes of all lumbar and last fourteen or fifteen 
dorsal vertebras. 

Insertion. — Internal tuberosity of body of humerus. 

Action. — Carries arm backward and upward, also in forced inspira- 
tion. 

Nerve. — Eighth cervical. 

SERRATUS ANTICUS MINOR. 

Origin. — Dorsal spinous processes from second to thirteenth. 
Insertion. — External surface of ribs from fifth to fourteenth. 
Action. — Raises ribs in inspiration. 
Nerve. — I ntercostals. 

SERRATUS POSTICUS MINOR. 

Origin. — Spinous processes of dorsal vertebrae from tenth to eight- 
eenth, and few lumbar vertebrae. 

Insertion. — External face of last nine ribs. 

Action. — Draws ribs upward and backward in expiration. 

Nerve. — I ntercostals. 

ILIO-SPINALIS (LONGISSIMUS DORSI OF PERCIVAL). 

Origin. — Lumbar border, external angle and internal surface of 
ilium, and spinous processes of all lumbar, dorsal and last four cervi- 
cal vertebrae. 



MYOLOGY. 63 

Insertion. — Transverse processes of lumbar vertebras and outer 
surfaces of fifteen or sixteen last ribs. 

Action. — Extends vertebral column and pulls ribs forward in expi- 
ration. 

Nerve. — Superior dorsal. 

COMMON INTERCOSTAL. 

Origin. — Runs from external surface of one rib to the next ; the 
anterior fasciculus ; into the last cervical vertebra. 
Action. — Depresses ribs. 
Nerve. — Intercostal. 

TRANSVERSE SPINOUS OF BACK AND LOINS. 

Origin. — Lateral lip of sacrum, articular tubercles of lumbar and 
transverse processes of dorsal vertebrae. 

Insertion. — Spinous process of sacral, lumbar, dorsal and last cer- 
vical vertebrae. 

Action. — Extensor of spine. 

Nerve. — Superior dorsal. 



COSTAL REGION. 

Here are found 54 muscles : — 

(1) 17 external intercostals ; (2) 17 internal intercostals ; (3) 17 
supercostals ; (4) serratus magnus ; (5) costo-transversalis, and (6) 
triangularis sterni. 

EXTERNAL INTERCOSTALS. 

Origin. — Downward and backward from posterior border of rib in 
front. 

Insertion. — Anterior border of rib behind. 
Action. — Muscles of inspiration. 
Nerve. — Intercostal. 

§ INTERNAL INTERCOSTALS. 

Origin. — Downward and forward, crossing preceding from inner 
and anterior border of rib behind. 

Insertion. — Posterior border of rib in front. 
Action. — Muscles of expiration. 
Nerve. — Intercostals. 



64 EQUINE ANATOMY. 

SUPER-COSTALS. 

Origin. — From transverse processes of dorsal vertebrae. 
Insertion. — External surface of one or two ribs below. 
Action. — Draw ribs forward in inspiration. 
Nerve. — Superior dorsal. 

SERRATUS MAGNUS. 

Origin. — External surface of first eight ribs. 

Insertio7i. — Anterior and posterior triangular surfaces of scapula 
and subscapularis. 

Action. — Acts to support body as a girdle or depresses scapula. 
Nerve. — Superior thoracic. 

TRANSVERSE COSTAL. 

Origin. — External face of first rib. 
Insertion. — Fourth costal cartilage and sternum. 
Action. — Raises ribs and enlarges thorax. 
Nerve. — Intercostal. 

TRIANGULARIS STERNI. 

Origin. — From superior border of sternum. 
Insertion. — Cartilages of true ribs except first. 
Action. — Expiratory muscle by depressing cartilages. 
Nerve. — Intercostal. 

DIAPHRAGM. 

The muscular partition between the thoracic and abdominal cavities. 

Origin. — By right and left pillars from lumbar vertebrae, confounded 
with inferior common ligament of the spine. (Between two pillars 
pass posterior aorta and thoracic duct.) From xiphoid appendix of 
sternum and anterior extremities of last twelve ribs. 

Insertion. — Phrenic centre, dividing into right and left leaflets. 

Relations. — Anteriorly, with pleurae and lungs ; posteriorly \ peri- 
toneum, stomach, liver, colon and spleen. 

Openings. — Behind for aorta and thoracic duct ; in right leaflet for 
vena cava ; in right pillar for oesophagus. 

Nerves. — Phrenic. 

Action. — Muscle of respiration. 



MYOLOGY. 65 

ABDOMINAL REGION. 

EXTERNAL OBLIQUE. 

Origin. — External surface of thirteen or fourteen lower ribs and 
aponeurosis of latissimus dorsi. 

Insertion. — Into linea alba and pre-pubic tendon. A number of 
strong fibres are reflected from the pubes to the anterior superior spine 
of the ilium, forming Ponparf s ligament. 

Action. — Compresses abdominal viscera, flexes spine and acts as 
muscle of forced expiration. 

Nerve. — Intercostal and lumbar. 

INTERNAL OBLIQUE. 

Origin. — Aponeurosis of latissimus dorsi ; external angle of ilium ; 
outer fourth of Poupart's ligament, and external face of last few ribs. 

Insertion. — Linea alba ; the fibres separating inferiorly to form part 
of the inguinal canal. 

Actio?i. — Same as preceding. 

Nerve. — Intercostal and lumbar. 

RETRACTOR OF LAST RIB. 

Origin. — From transverse processes of first two or three lumbar 
vertebrae 

Insertion. — Posterior border of last rib. 
Action. — Fixes last rib. 
Nerve. — Lumbar. 

TRANSVERSALIS. 

Origin. — Internal surface of asternal ribs, and transverse processes 
of lumbar vertebra}. 

Insertion. — Into tinea alba (or middle aponeurosis of abdominal 
tunic) and crural arch. 

Action. — Same as oblique muscles. 

Nerve. — Intercostal and lumbar. 

RECTUS ABDOMINIS. 

Origin. — To cartilages of fifth, sixth, seventh, eighth, and ninth 
ribs, and inferior face of sternum. 

Insertion. — To common tendon into pubes. 



66 EQUINE ANATOMY. 

Action. — Draws pelvis forward, thorax backward ; flexes spine and 
compresses abdomen. 
Nerve. — Intercostal. 



INGUINAL CANAL. 

A canal on each side and in front of the pubic bone, running 
downward, backward and inward, which transmits the spermatic 
cord and vessels in the male, and the external mammary vessels in 
the female. 

Has an external or scrotal, and internal or peritoneal ring, and two 
pillars. 

ANTERIOR EXTREMITY. 

SUPERFICIAL PECTORAL. 

Composed of two parts. 

(A) Sterno-humeralis. 

Origin. — Anterior appendage and inferior border of sternum. 
Insertion. — Anterior ridge of humerus. 
Action. — Abductor of anterior limb. 
Nerve. — Inferior thoracic. 

(B) Sterno-aponeuroticus. 
Origin. — Inferior surface of sternum. 

Insertion. — With preceding, and also into fascia of limb. 
Action. — Same as preceding, and tensor of brachial fascia. 
Nerve. — Inferior thoracic. 



DEEP PECTORAL. 

Composed of two parts. 

(A) Sterno-trochineus. 

Origin. — Abdominal tunic and posterior two-thirds of inferior border 
of sternum. 

Insertion. — Internal tubercle of head of humerus, fascia of coraco- 
brachialis and coraco-radialis, and lip of bicipital groove. 

Action. — Pulls limb backward. 

Nerve. — Inferior thoracic. 



MYOLOGY. 67 

(B) Sterno-prescapularis. 

Origin. — Sides of inferior border of sternum, and cartilages of first 
three or four ribs. 

Insertion. — Supra- spinatous fascia. 

Action. — Pulls scapula backward and downward. 

Nerve. — Sixth and seventh cervical. 

AXTEA SPINATUS. 

Origin. — Ante-spinous fossa. 

Insertion. — By two tendons into external and internal humeral 
tubercles. 

Action. — Extensor of humerus. 
Nerve. — Sixth and seventh cervical. 

POSTEA SPINATUS. 

Origin. — Postea-spinous fossa, acromion spine and tuberosity. 
Insertion. — External humeral tuberosity. 
Action. — Abductor and external rotator. 
Nerve. — Sixth and seventh cervical. 

TERES MAJOR. 

Origin. — One head from dorsal angle and the other from aponeu- 
rosis and tuberosity of spine of scapula. 
Inse?'tion. — Deltoid imprint of humerus. 
Action. — Abductor and external rotator. 
Nerve. — Eighth cervical. 

TERES MINOR. 

Origin. — Posterior border and postea spinous fossa of scapula and 
margin of glenoid cavity. 

Insertion. — Humerus between external and deltoid tuberosities. 
Action. — Like preceding. 
Nerve. — Circumflex. 

SUBSCAPULARS. 

Origin. — Subscapular fossa. 
Insertion. — Internal tubercle of humerus. 
Action. — Adductor and internal rotator. 
Nerve. — Seventh cervical. 



68 EQUINE ANATOMY. 

ADDUCTOR OF THE ARM. 

Origin. — Dorsal angle of humerus and subscapularis. 
Insertion. — Circular imprint of humerus. 
Action. — As name implies, also internal rotator. 
Nerve. — Eighth cervical. 

CORACO-BRACHIALIS. 

Origin. — Coracoid process. 

Insertion. — Above internal tuberosity and anterior face of humerus. 

Action. — Adductor, internal rotator. 

Nerve. — Musculo-cutaneous. 

SMALL SCAPULO-HUMERALIS. 

Origin. — Above glenoid cavity. 

Insertion. — Into capsular ligament. 

Action. — Raises capsular ligament during flexion. 

Nerve. — Subscapular. 



BRACHIAL REGION. 

CORACO-RADIALIS. 

Origin. — Coracoid process through bicipital groove. 
Insertion. — Bicipital tuberosity on superior and inner border ot 
radius, capsular and internal lateral ligament. 
Action. — Flexes forearm. 
Nerve. — Musculo-cutaneous. 

HUMERO-RADIALIS. 

Origin. — Posterior face of humerus below head. 

Insertion. — Passes through groove on radius under .internal lateral 
ligament into upper end of radius and ulna. (Winds through twisted 
furrow of humerus.) 

Actio7i. — Flexes forearm. 

Nerve. — Radial. 

LONG EXTENSOR OF FOREARM. 

Origin. — Aponeurosis from posterior border of scapula. 
Insertion. — Posterior border of ulna and antibrachial aponeurosis. 



MYOLOGY. . 69 



Action. — Extends forearm. 
Nerve. — Radial. 



LARGE EXTENSOR OF FOREARM. 

Origin, — Dorsal angle and axillary border of scapula. 
Insertion. — Into olecranon, after gliding over a bursa. 
Action. — As preceding. 
Nerve. — Radial. 

SHORT EXTENSOR OF FOREARM. 

Origin. — Line running from head of humerus to deltoid. 
Insertion. — Imprint with preceding. 
Action. — With preceding. 
Nerve. — Radial. 

MIDDLE EXTENSOR OF FOREARM. 

Origin. — Inner surface of humerus above tuberosity. 
Insertion. — Tip and side of olecranon. 
Actio7i. — As preceding. 
Nerve. — Radi al . 

ANCONEUS. 

Origin. — Above margin of olecranian fossa. 
Insertion. — Anterior and external border of olecranon. 
Action. — Raises capsule of humero-ulnar-radial articulation. 
Nerve. — Radial. 

FOREARM. 

The anii-brachial aponeurosis is a strong layer of fibrous tissue that 
binds the muscles of the forearm together and passes between them, 
forming the inter-muscular septum. It is attached to the olecranon 
and sides of radius. 

ANTERIOR EXTENSOR OF THE METACARPUS. 

Origin. — From humerus below crest of furrow of torsion, and above 
and in front of the inferior articular portion. 

Insertion. — Anterior and superior tuberosity of large metacarpal 
bone. 

Action. — As name implies. 

Nerve. — Radial. 



yo 



EQUINE ANATOMY. 



Fig. 7. 




OBLIQUE EXTENSOR OF METACARPUS. 

Origin. — External surface of radius. 

Insertion. — Head of internal meta- 
carpal with internal lateral ligament. 

Action. — Extends metacarpus and 
rotates them outward. 

Nerve. — Radial. 

ANTERIOR EXTENSOR OF PHALANGES. 

Origin. — Below crest of furrow, of 
torsion, of humerus, and in front of 
its inferior extremity ; the external 
lateral ligament of elbow and ex- 
ternal tuberosity and border of radius. 

Insertion. — Pyramidal eminence of 
third phalanx, capsular ligament of 
fetlock-joint and anterior surfaces of 
first and second phalanges. 

Action. — As name implies. 

Nerve.— -Radial. 

Fig. 7. — EXTERNAL MUSCLES OF THE RIGHT 
ANTERIOR LIMB. 

i, Long abductor of the arm; i', Its humeral 
insertion; 2, Superspinatus ; 3, Subspinatus ; 
3', Its tendon of insertion ; 4, Short abductor 
of the arm; 5, Biceps ; 6, Anterior brachialis; 
7, Large extensor of the forearm ; 8, Short 
extensor of the forearm; 9, Anconeus; 11, 
Anterior extensor of the metacarpus ; 11', Its 
tendon; 12, Aponeurosis separating that mus- 
cle from the anterior brachialis ; 13, Oblique 
extensor of the metacarpus ; 14, Anterior ex- 
tensor of the phalanges ; 14', Its principal 
tendon; 15, The small tendinous branch it 
furnishes to the lateral extensor; 16, Lateral 
extensor of the phalanges ; 16', Its tendon ; 
17, The fibrous band it receives from the 
carpus ; 18, External flexor of the metacarpns ; 
19, Its metacarpal tendon ; 20, Its supracarpal 
tendon; 21, Ulnar portion of the perforans; 
22, Tendon of the perforans; 23, Its carpal 
ligament ; 24, Its reinforcing phalangeal sheath ; 
25, Tendon of the perforatus. 



MYOLOGY. 71 

LATERAL EXTENSOR OF PHALANGES. 

Origin. — Outer side of superior tuberosity of radius ; from contigu- 
ous sides of radius and ulna and external lateral ligament. 

Insertion. — Anterior surface of superior portion of first phalanx. 
Action. — As preceding. 
Nerve. — Radial. 

EXTERNAL FLEXOR OF METACARPUS. 

Origin. — External condyle of humerus. 

Insertion. — Supercarpal and external metacarpal bones. 

Action. — Flexes foot. 

Nerve.— Radial. 

OBLIQUE FLEXOR OF METACARPUS. 

Origin. — Base of epitrochlea and olecranon. 
Insertion. — On supercarpal with preceding. 
Action. — As preceding. 
Nerve. — Ulnar. 

INTERNAL FLEXOR OF METACARPUS. 

Origin. — Epitrochlea with preceding. 
Insertion. — Head of internal metacarpal bone. 
Action. — Same as external flexor. 
Nerve. — Radial. 

FLEXOR SUBLIMIS DIGITORUM OR PERFORATUS. 

Origin. — Summit of epitrochlea. 

Insertion. — By two divisions into superior extremity of second pha- 
lanx ; between the two divisions pass the perforans tendon. It also 
passes through the carpal sheath, a reflection of strong fibres running 
from the first to the fourth carpal bones. 

Action. — Flexes second phalanx and also whole foot. 

Nerve. — Ulnar. 

FLEXOR PROFUNDUS DIGITORUM OR PERFORANS. 

Origin. — Summit of epitrochlea, summit and posterior border of 
olecranon and posterior surface of radius. 

Insertion. — Passes through carpal sheath, between two heads of 



72 EQUINE ANATOMY. 

perforates, and is attached by means of plantar aponeurosis into semi- 
lunar crest of os pedis. 

Action. — Flexes third phalanx and also whole foot. 

Nerve. — Ulnar. 

ANTERIOR FOOT. 

They comprise two lumbricales and two interossei. 

LUMBRICALI. 

Origin. — From right and left side of perforans tendon. 
Insertion. — Into fibrous tissue of the fetlock. 

INTEROSSEI. 

Origin. — Anteriorly between metacarpal bones. 
Insertion. — Into anterior extensor of phalanges. 
Action. — With extensor. 
Nerve. — Ulnar. 

POSTERIOR EXTREMITY. 

Pelvic Region. — great psoas. 

Origin. — From bodies of last two dorsal and first five lumbar verte- 
brae, inferior surface of two last ribs and lumbar transverse processes. 
Insertion. — Internal trochanter. 
Action. — Flexor and external rotator of thigh. 
Nerve. — Iliaco-muscular. 

ILIO-PSOAS. 

Origin. — Whole iliac surface, external iliac angle, sacro-iliac liga- 
ment and ilio-pectineal crest. 
Insertion. — With preceding. 
Action. — Same. 
Nerve. — Iliaco-muscular. 

SMALL PSOAS. 

Origin. — Bodies of three or four last dorsal and all lumbar verte- 
brae. 

Insertion. — Ilio-pectineal eminence and ilio-lumbar aponeurosis. 
Action. — Flexes pelvis on spine, or spine on pelvis. 
Nerve. — Iliaco-muscular. 




73 



MUSCLES OF THE SUB-LUMBAR, PATELLAR. AND INTERNAL CRURAL REGIONS. 



Psoas magnus ; i', Its terminal tendon ; 2, Psoas parvus ; 3, Iliacus ; 4, Its small internal 
portion ; 5, Muscle of the fascia lata ; 6, Rectus of the thigh ; 7, Vastus internus ; 
8, Long adductor of the leg; 9, Short adductor of the leg; 11, Pectineus ; 12, Great 
adductor of the thigh; 12', Small adductor of the thigh; 13, Semimembranosus; 
14, Semitendinosus. — a, Portion of the iliac fascia ; b, Portion of the layer reflected 
from the aponeurosis of the abdominal great oblique, forming Poupart's ligament; 
c, Pubic tendon of the abdominal muscles; d, Origin of the pubo-femoral ligament. 

6 



74 EQUINE ANATOMY. 

QUADRATUS LUMBORUM. 

(A) Primary Fasciculus. 
Origin. — Sacro-iliac ligament. 

Insertion. — Last rib and transverse lumbar processes. 

(B) Secondary Fasciculus. 

Origin. — From first. 

Insertion. — Lumbar transverse processes and last two or three ribs. 
Action. — Draws last ribs backward and inclines spine laterally. 
Nerve. — Lumbar. 

INTER-TRANSVERSE OF LOINS. 

Runs between lumbar transverse processes. 
Action. — Inclines lumbar region laterally. 
Nerve. — Lumbar. 



Gluteal Region. — superficial gluteal. 
Origin. — Internal aspect of gluteal aponeurosis, postero-external 
iliac angle and ischiatic ligament. 

Insertion. — Third trochanter of femur. 

Action. — Abductor and external rotator of femur. 

Nerve. — Anterior gluteal. 

MIDDLE GLUTEAL. 

(Largest of three.) 

Origin. — Gluteal aponeurosis, superior face and external angles of 
ilium, sacro-iliac and sacro-sciatic ligaments. 
Insertion. — Trochanter major. 
Action. — Abductor of thigh, or assists in rearing. 
Nerve. — Anterior gluteal. 

DEEP GLUTEAL. 

Origin. — Neck of ilium and supra-cotyloid ridge. 
Insertion. — Convexity of trochanter. 
Action. — Abductor and internal rotator. 
Nerve. — Posterior gluteal. 



MYOLOGY. 75 

Thigh. — tensor vagina femoris. 

Origin, — External angle of ilium. 

Insertion, — Into the strong fascia covering and running between 
the muscles of the thigh, the fascia lata. 

Action. — Flexes thigh and renders fascia lata tense. 
Nerve. — Anterior gluteal. 

CRURAL TRICEPS. 

(A) Rectus. 

Origin. — Lip of cotyloid cavity. 
Insertion. — Into patella. 

(B) Vastus Externus. 

Origin. — Outer and anterior surfaces of femur. 
Insertion. — As above. 

(C) Vastus Internus. 

Origin. — Inner and anterior surfaces of femur. 
Insertion. — As above. 
Action. — Extensor of leg. 
Nerve. — Posterior gluteal. 

ANTERIOR GRACILIS. 

Origin.— From ilium near origin of rectus. 
Insertion. — Into capsular ligament of hip joint. 
Action. — Makes tense capsule of joint. 
Nerve. — Ilio-m uscular. 

LONG VASTUS. 

(A) Anterior portion. 

Origin. — Sacral spine, sacro-sciatic ligament, tuberosity of ischium 
and coccygeal aponeurosis. 

Iisertion. — Below subtrochanteric crest of femur and side of patella. 
Action. — Pulls femur backward and patella outward. 

(B) Posterior portion. 

Origin. — Spine and tuberosity of ischium. 
Insertion. — Crest of tibia and tibial fascia. 
Action. — Flexes leg and makes tense fascia. 
Nerve. — Great sciatic. 



j6 EQUINE ANATOMY. 

SEMI-TENDINOSUS. 

Origin. — From sacral spine, sacro-sciatic ligament (with long 
vastus) and tuber ischii. 

Insertion. — Anterior crest of tibia. 
Action. — Same as preceding. 
Nerve. — Great sciatic. 

SEMI-MEMBRANOSUS. 

Origin. — Tuberosity and inferior face of body of ischium and 
coccygeal aponeurosis. 

Insertion. — Eminence above internal condyle of femur. 

Action. — Adductor and extensor of thigh and an adjunct in rear- 
ing. 

Nerve. — Great sciatic. 

Internal Femoral Region. — Sartorius. 
Origin. — Iliac aponeurosis near tendon of psoas parvus. 
Insertion. — Internal patellar ligament. 
Action. — Adducts leg and flexes femur. 
Nerve. — Obturator. 

GRACILIS. 

Origin. — Ischio-pubic symphysis. 

Insertion. — With preceding and internal tuberosity of tibia. 
Action. — Adductor of leg and tensor of tibial aponeurosis. 
Nerve. — Obturator. 

PECTINEUS. 

Origin. — Inferior face of pubes or pubo-femoral ligament. 
Insertion. — Inner surface of femur near nutrient foramen. 
Action. — Adductor, flexor and internal rotator of femur. 
Nerve. — Obturator. 

ADDUCTOR brevis. 
Origin. — Inferior face of pubis. 

Insertion. — Quadrilateral line on posterior surface of femur. 
Action. — As name implies. 
Nerve. — Obturator. 

ADDUCTOR LONGUS. 

Origin. — Lower face of ischium and symphysis. 
Insertion. — With preceding, and internal condyle of femur. 
Action. — Adductor, extensor and external rotator of thigh. 
Nerve. — Obturator. 



MYOLOGY. 77 

QUA DRAT US FEMORIS. 

Origin. — Tuber ischii. 

Insertion. — Posterior surface of femur, below trochanter. 

Action. — Extensor and adductor of femur. 

Nerve. — Great sciatic. 

EXTERNAL OBTURATOR. 

Origin. — Below margin of obturator foramen. 
Insertion. — Trochanterian fossa. 
Action. — Adductor and external rotator. 
Nerve. — Obturator. 

INTERNAL OBTURATOR. 

Origin. — Above margin of obturator foramen. 
Insertion. — Trochanterian fossa. 
Actio7i. — Abductor and external rotator. 
Nerve. — Great sciatic. 

GEMELLI. 

Origin. — Above and below tendon of obturator internus, from 
ischium. 

Insertion. — Into tendon of internal obturator. 
Action. — Like preceding. 
Nerve. — Great sciatic. 

ANTERIOR EXTENSOR OF PHALANGES. 

Origin. — Digital fossa above external condyle of femur. 

Insertion. — Capsular ligament of metatarsophalangeal articulation, 
anterior surfaces of first two phalanges and pyramidal eminence of 
os pedis. 

Action. — Extends digit. 

Nerve. — External popliteal. 

LATERAL EXTENSOR OF PHALANGES. 

Origin. — External femoro-tibial ligament and whole extent of 
fibula. 

Insertion. — Terminates in tendon of interior extensor. 
Action. — As preceding. 
Nerve. — External popliteal. 



78 



EQUINE ANATOMY. 
Fig. 9. 




MUSCLES ON INNER ASPECT OF LEFT POSTERIOR LIMB. 

i, Crest of the ilium; 2, Section through it; 3, Sacro-ischiatic ligament; 4, Pyriformis ; 
5, Posterior portion of sacro-ischiatic ligament; 6, Tuberosity of ischium; 7, Anterior 
portion of ischium, sawn through; 8, Pubis ; 9, Obturator foramen; 10, External iliac 
artery and vein, 11; 12, Obturator artery and vein; the figures are placed on the 
internal obturator muscle ; 13, Long adductor of the leg, or sartorius ; 14, Small adduc- 
tor of the thigh, or adductor brevis ; 15, Short adductor of the leg, or gracilis ; 16, Rectus 
of the thigh; 17, Vastus internus ; 18, Patella, with insertion of rectus; 19, Upper 
extremity of tibia ; 20, Gastrocnemius; 21, Popliteus ; 22, Oblique flexor of the pha- 



MYOLOGY. 79 

FLEXOR OF METATARSUS. 

(A) Tendinous Portion. 

Origin. — From front of femur between trochlea and external con- 
dyle. 

Insertion. — Front of superior extremity of principal metatarsal and 
cuboid. 

Action. — Flexes metatarsus and hock joint. 

(B) Muscular Portion. 

Origin. — From tibia on sides of groove for tendinous portion. 
Insertion. — In front of superior extremity of principal metatarsal 
and second cuneiform bone. 
Nerve. — Anterior tibial. 

GASTROCNEMII. 

Origin. — External head from above and behind external condyle. 
Internal from internal condyle. 

Insertion. — Into posterior part of summit of os calcis after passing 
over a bursa. 

Action. — Extends foot on tibia. 

Nerve. — Great sciatic. 

SOLEUS. 

Origin. — External tuberosity of tibia. 
Insertion. — Into tendon of preceding. 
Action. — As preceding. 
Nerve. — Great sciatic. 

FLEXOR SUBLIMIS DIGITORUM OR PERFORATUS. 

Origin. — Above super-condyloid fossa of femur. 
Insertion. — Into summit of os calcis and fibrous band of hock, then 
spreads out on second phalanx. 

Action. — Flexes second phalanx and extends foot. 
Nerve. — Plantar. 



langes, or flexor pedis accessorius, with its tendon, 34; 23, Perforans muscle, with its 
tendon, 35 ; 24, Flexor metatarsi ; 25, Anterior extensor of the phalanges, or extensor 
pedis ; 26, Annular ligament ; 27, Tendon of flexor metatarsi, and its cunean branch, 28 ; 
29, Tendon of superficial flexor or internal gastrocnemius ; 30, Tendon of gemelli or 
external gastrocnemius ; 31, Os calcis ; 32, Astragalus; 33, Perforatus tendon; 34, Ten- 
don of oblique flexor joining the perforans tendon, 35; 36, Large metatarsal bone; 
37, Extensor pedis tendon ; 38, Terminal knob of small metatarsal bone. 



80 EQUINE ANATOMY. 

POPLITEUS. 

Origin. — Outside external condyle of femur. 

Insertion. — Into triangular surface on posterior surface of tibia at 
its upper portion. 

Action. — Flexes tibia and rotates it outward. 
Nerve. — Great sciatic. 

FLEXOR PROFUNDUS DIGITORUM OR PERFORANS. 

Origin. — To external tuberosity and posterior surface of tibia, fibula 
and interosseous ligament. 

Insertion. — Passes through tarsal sheath on inner side of os calcis 
and into semilunar crest of os pedis. 

Action. — Flexes phalanges on each other and on metatarsus. 

Nerve. — Great sciatic. 

OBLIQUE FLEXOR OF PHALANGES. 

Origin. — External tuberosity of tibia. 
Insertion. — Upper third of metatarsus. 
Action. — With preceding. 
Nerve. — Great sciatic. 

POSTERIOR FOOT. 

Two lumbricales and two interossei, as in anterior foot. 



PEDAL MUSCLE. 

Origin. — Lower end of os calcis and astragalus. 
Insertion. — Into tendons of extensors of phalanges. 
Action. — Aids in extending digit and flexing hock. 
Nerve. — Plantar. 

Coccygeal Region. — (3 pairs.) sacro-coccygeus superior. 
Origin. — From sides of spinous processes of last 3 or 4 sacral ver- 
tebrae. 

Insertion. — Into coccygeal vertebras. 

Action. — Elevates tail or carries it to one side. 

Nerve. — Coccygeal. 



CIRCULATORY APPARATUS. 8 1 

SACRO-COCCYGEUS INFERIOR. 

Origin. — From third portion of sacrum, internal surface of sacro- 
sciatic ligament. 

Insertion. — Under surface of coccygeal vertebrae. 
Action. — Depresses tail or carries it to one side. 
Nerve. — Coccygeal. 

SACRO-COCCYGEUS LATERALIS. 

Origin. — Spinous processes of last lumbar vertebrae. 
Insertion. — Sides of coccygeal vertebrae. 
Action. — Carries tail to one side. 
Nerve. — Coccygeal. 

ISCHIO-COCCYGEUS. 

Origin. — Internal face of sacro-sciatic ligament and sciatic crest. 
Insertion. — Last sacral and first two coccygeal vertebrae. 
Action. — Depresses whole tail. 
Nerve. — Coccygeal. 



CIRCULATORY APPARATUS. 

PERICARDIUM. 

A fibro-serous membrane enveloping the heart and favoring its 
movements by its polished surfaces. Fibrous layer attached by its 
apex to the sternum, from the fourth rib to the xiphoid appendix. 

By its base to the great vessels of the neck and continuous with the 
fascia of the neck. 

Serous layer composed of a layer of flattened epithelium on a base- 
ment membrane. It is composed of two divisions, a visceral and 
parietal. The parietal layer is reflected on the fibrous sac, and the 
visceral over the heart itself. Amount of fluid in sac very small. 

Blood supply from mediastinal arteries. 

Nerves from sympathetic. 

HEART. 
The heart is the propelling organ of the blood. It is a hollow 
muscle placed in the thorax opposite the third, fourth, fifth and sixth 
ribs, between and below the lungs. It is conoidal in shape, 10 inches 
long and 7^ inches wide. Weight, 6% lbs. 



4S?<i> 



82 



EQUINE ANATOMY. 



Fig. 




THE HEART AND PRINCIPAL VESSELS; LEFT FACE. 



Right ventricle ; b, Left ventricle ; c, Right auricle ; d, Left auricle ; e, Pulmonary 
artery ; e' ', Obliterated arterial canal ; f, Pulmonary veins ; g, Anterior aorta ; h, Left 
axillary artery ; z", Right axillary artery, or brachio-cephalic trunk; j, Origin of the 
dorsal artery; k, Origin of the superior cervical artery; /, Origin of the vertebral 
artery; in, Origin of the inferior cervical artery; n, Origin of the internal thoracic 
artery; o, Origin of the external ditto; p, Carotid arteries ; q, Posterior aorta ; r, An- 
terior vena cava ; s, Trunk of the axillary vein ; t, Trunk of the internal thoracic vein ; 
«, Trunk of the dorso-cervical vein; v, Posterior vena cava; v' , Embouchure of the 
hepatic and diaphragmatic veins; x> Vena azygos; y, Thoracic duct; 0, Embouchure 
of that vessel, placed near the origin of the anterior vena cava. 1, Right cardiac 
artery; 2, Left cardiac artery; 3, Auriculo-ventricular branch of the latter; 4, Its 
ventricular branch ; 5, Cardiac vein. 



CIRCULATORY APPARATUS. 83 

Cavities. — It is divided by a vertical septum into two parts, which 
are further divided into four by a transverse septum, 

The cavities above the transverse septum are called the right and 
left auricles. 

Those below, the right and left ventricles. 

RIGHT AURICLE. 

On an average the walls are one-fourth of an inch thick. It receives 
the anterior vena cava, posterior cava vena azygos, and the large 
coronary veins, and opens into the interior of the auricular appendix, 
a mass projecting from the outside of the auricle. Its interior is 
divided by a number of transverse bands called musculi pectinati. 

On the posterior wall is the fossa ovalis, the remains of the opening 
existing in fcetal life ; around its periphery is found the annulus ovale 
or ring. 

Behind the anterior cava is an eminence, the tuberculinn Louucri. 
The anterior border of the fossa ovalis shows a fold called the Eus- 
tachian valve, a remnant of fcetal life. 

The auriculo-ventricular opening is found on its floor, circular in 
outline, surrounded by a fibrous ring and closed by the tricuspid 
valve. 

RIGHT VENTRICLE. 

The walls are, on an average, ^ of an inch thick. The apex ex- 
tends to only 1% inches from the point of the heart. The walls are 
uneven from the columnae carnece \ or muscular columns, which project 
into the cavity. They are of three varieties, one attached by one end 
and the other prolonged by the chordae tendinae, to the edges of the 
valves ; the second, by both extremities ; the third, adherent through 
all its length. 

The tricuspid valve closes the opening into the auricle, and is 
composed of three segments, all attached to the chordce tendince. 

The pulmonary opening is circular and leads into the pulmonary 
artery. It is closed in by the semihmar valves, three in number, 
which are attached also to the tendinous cords. In the centre of each 
valve is often seen an elevation, the corpus arantii. 

LEFT AURICLE. 

Much similar in structure to that of the right side. It opens into the 
left ventricle, and has on its superior wall the openings of four to eight 



84 EQUINE ANATOMY. 

pulmonary veins, which have no valves. The obliterated foramen 
ovale is also seen on the inter-auricular septum. 

LEFT VENTRICLE. 

The walls are on an average ii to if inches in thickness, at the 
apex they are very thin and form the point of the heart. 

The auriculo-ventricular opening, similar to that on the right side, 
is closed by the mitral valve, composed of two segments attached to 
chordae tendinae. 

The aortic opening is similar to the one on the right, and is closed 
by the semilunar valves. 

Structure. 

Four fibrous rings around the openings. 

At the junction of the aortic and auriculo-ventricular rings is a car- 
tilaginous body. 

The muscular tissue is striped and involuntary, but unlike all vol- 
untary tissue, it inosculates and branches freely, has no sarcolemma 
and its striae are not well marked. 

The auricles have two sets of fibres, one common to both, the other 
of fasciculi arranged in loops, rings, or as sphincters. 

The ventricles have also two sets, one intrinsic running from the 
rings obliquely around the axis of the ventricle, the other common to 
both, running downward, and from left to right terminating internally 
in the columnce carnece. 

The endocardium is a serous membrane lining the cavities of the 
heart, having a basement membrane covered with flattened endothe- 
lium, polygonal in form, each with a nucleus. Its reduplications form 
the valves. 

Blood supply. 

Coro?iary arteries, from trunk of the aorta, each following the 
horizontal and vertical furrows. The venous blood is returned to the 
right auricle by the coronary vein. 

Nerves, 

From pneumogastric and sympathetic. Probably also intra-cardiac 
sympathetic ganglia. 



CIRCULATORY APPARATUS. 85 

ARTERIES. 

The arteries are the tubes that carry arterial blood from the heart 
over the body. 

The pulmonary artery carries venous blood to the lungs, forming 
with the corresponding veins the pulmonary circulation. The re- 
mainder of the arteries constitute the general or systemic circulation. 

Structure of arteries. 

They are more or less rigid and elastic, with three coats, — 0) an 
external fibrous or adventitia, (2) a middle muscular or media, (3) 
an internal serous or intima, continuous with the endocardium. 

The external tunic is nourished by vasa vasorum, and the muscular 
coat receives branches from the sympathetic system, called vasomotor 
nerves. 

The capillaries are small vessels between the arterial and venous 
systems. They are composed of a basement membrane, covered by 
a layer of delicate cells, continuous with those of the arteries. 

THE AORTA. 

It is the beginning of the arterial system, given off from the left 
ventricle, and guarded by the semilunar valves. Just above the 
valves it shows three dilatations, the sint/ses of Valsalva. It passes 
upward and forward for about two inches, when it divides into the 
anterior and posterior aortas. 

Branches. 

Right and left coronary to heart (see above). 

ANTERIOR AORTA. 

The smaller of the two passes forward and upward for two or two 
and a half inches, where it divides into the two axillary arteries or 
brachial trunks. 

The right is much the larger, and gives off the carotid arteries. 

Course. 

They curve forward and outward over the anterior border of the first 
rib below the scaleni, accompanied by the brachial nerves to the space 
between the sub-scapularis and the adductor of the arm, where it be- 
comes the humeral artery. 



86 EQUINE ANATOMY. 

Branches. — From thoracic portion. 

i. Dorsal or transverse cervical. 

To muscles and integument of the withers, neck and shoulders. It 
gives off the sub-costal, which sends branches to the second, third 
and fourth intercostal spaces. 

2. Superior or deep cervical. 

Passes between two first ribs to muscles of neck or back, to spinal 
cord and first intercostal space. 

j. Vertebral. 

Through foramina of the upper six cervical vertebrae, anastomosing 
with the occipital, and giving off muscular and spinal branches, called 
superior, inferior, external and internal. 

4. Internal thoracic or internal mammary. 

Given off near the first rib ; runs above the costal cartilages to the 
xiphoid appendix. 

Branches. 

Superior to pericardium and mediastinum ; inferior to pectoral 
muscles', external or intercostal ; anterior abdominal passes into rectus 
muscle and anastomoses with post-abdominal. 

Asternal artery to thirteenth intercostal space, anastomosing with 
artery ; gives off abdominal, intercostal and diaphragmatic branches. 

5. External thoracic or external maifwiary. 

Given off in front of preceding, curving around first rib ; supplies 
pectoral and other muscles of chest. 

6. Inferior cervical. 

Given off opposite the two preceding ; divides into two branches, 
superior (ascending cervical) to muscles and glands of neck, and 
inferior (acromio-thoracic) to pectoral muscles. 

7. Superior scapular. 

Given off near sub-scapular tendon ; passes up and terminates in 
scapular muscles and shoulder joint. 

8. Sub-scapular. 

Given off at junction of axillary portion with humeral artery ; passes 
up and backward near the dorsal angle of scapula. 

Branches. 

One to latissimus dor si. 

Muscular branches to scapular muscles. 

Scapulo-hiwieral to muscles of shoulder and arm. 



CIRCULATORY APPARATUS. 87 

HUMERAL ARTERY. 

From posterior border of sub-scapularis muscle to above inferior 
articular surface of the humerus, where it terminates in the anterior 
and posterior radial arteries. 

It is in relation to the median nerve on the outside and the coraco- 
radialis on the inside. 

Its branches are — 

/. Prehuvieral or anterior circumflex of shoulder. 
To shoulder joint and muscles of upper humeral region, anasto- 
mosing with posterior circumflex. 

2. External collateral of elbow. 

To muscles in vicinity of elbow joint, where it anastomoses with 
anterior radial. 

3. Internal collateral or ulnar. 

To internal border of arm and forearm, to carpus, anastomosing 
with posterior radial, and accompanying the ulnar nerve and vein. 
It sends branches to muscles, to elbow joint and humerus. 

4. Coraco-radial. 
To muscle. 

ANTERIOR RADIAL. 

The smaller of two branches of humeral, extends along front of 
radius to front of carpus, where it splits up into smaller branches, 
which supply the articulation, and anastomose with posterior radial 
and interosseous. It gives off branches also to elbow joint and mus- 
cles. 

POSTERIOR RADIAL. 

The larger of two subdivisions of humeral, passes to side on internal 
ligament of elbow, along inner side of radius, to its inferior portion, 
where it divides into the common interosseous, metacarpal and col- 
lateral artery of the cannon. 

The branches in its course are to elbow and muscles of forearm. 

INTEROSSEOUS OF FOREARM. 

Arises near radio-ulnar arch, and passes along groove between 
ulnar and radius. Gives off branches to the elbow, anti-brachial 
muscles, and terminates at the carpus by numerous anastomoses. 



Fig. i 



^J 



\ 



V 



EQUINE ANATOMY. 
COMMON INTEROSSEOUS OF METACARPUS. 

Given off at inner side of, and descends behind, 
the carpus to the head of internal metacarpal, then 
passes outward, anastomosing with a descending 
branch from arch above between ulnar and 
common arteries, forming the sub-carpal arch. 
That above is the supra-carpal arch. 

Branches. 

Two posterior interosseous, arising at heads of 
metacarpus, pass downward, ending at lower ends 
of metacarpus, anastomosing with the collateral of 
the cannon, and giving off branches to the suspen- 
sory ligament, skin and tendons. 

Two anterior interosseous, arising with preced- 
ing, curve around heads of bones, become anterior, 
pass downward, anastomose with artery of cannon, 
and send branches to tendons and skin. 

COLLATERAL ARTERY OF CANNON. 

Passes under carpal sheath to inner side of 
flexor tendons, with internal plantar nerve, to top 
of great sesamoid bones, where it divides into the 
digital arteries. 



It 



*& 



Fig. II. — ARTERIES OF THE FORE-FOOT, SEEN FROM BEHIND. 

The muscles and tendons have been removed, only a small portion 
of the perforans tendon being left; the os pedis has been 
chiseled away on its plantar face to expose the semilunar 
anastomosis. 

i, Posterior radial artery; 2, Innominate carpal branch; 3, Supra- 
carpal arch; 4, Epicondyloid (ulnar) artery; 5, Radio-palmar 
artery, or common trunk of the interosseous metacarpal arte- 
ries ; 6, Sub-carpal arch; 7, 7, Posterior interosseous meta- 
carpal arteries ; 7', 7', Anterior interosseous metacarpal arte- 
ries ; 8, 8, Their origin ; 9, Collateral artery of the cannon ; 

10, Its communicating branch with the interosseous arteries ; 

11, 11, Digital arteries; 12, Semilunar anastomosis in the os 
pedis; 13, Emergent branches of this anastomosis; 14, Plantar 
ungueal artery, forming this anastomotic arch; 15, Origin ot 
the pre-plantar ungueal artery ; 16, Origin of the plantar- 
cushion artery; 17, Origin of the anterior branch of the 
coronary circle ; 18, Posterior branch of the same. 



CIRCULATORY APPARATUS. 89 

Branches. 

An anastomosing branch, with the internal collateral forming the 
supra- carpal arch above the pisiform bone. 

A few to the tendons and skin. 

One passing upward, anastomosing with the interossei. The digital 
vessels are similar to those of the posterior limb, with which they will 
be described. 

COMMON CAROTIDS. 

These two vessels supplying the head and neck, arise by a common 
trunk, from the right axillary at its origin, called the cephalic. This 
passes forward under the trachea to anterior entrance of the chest, 
where it divides into its two branches ; each common carotid passes 
upward along the trachea to the larynx, where it divides into the 
occipital, external and internal carotids. 

Branches. 

Small ones to the muscles, oesophagus and trachea. 

Thy to- laryngeal, to thyroid gland, larynx and pharynx. 

Accessory thyroid, to thyroid and cervical muscles. 

Occipital. 

Passes alongside of internal carotid, under inferior arch of atlas, 
through anterior foramen in its transverse process, dividing into 
occipito-niuscular and cerebro-spinal. 

Branches. 

Prevertebral, to muscles of neck and dura mater. 

Mastoid, through parietotemporal canal to dura and temporal 
muscle. 

Atloido-?nuscular, passes backward to anastomose with vertebral. 

Occipito-miiscitlar, inward to muscles and skin of occipital region. 

Cerebrospinal. 

Enters spinal canal and divides into two branches, one of which 
passes backward and unites with its fellow of the opposite side, form- 
ing the median spinal artery. The anterior branch unites with its 
fellow, forming the basilar. 

Basilar. 

Passes under the medulla, runs forward to the anterior border of 
the pons. 

Branches. 

Small vessels to pons, medulla and cranial nerves. 

7 



9 o 



EQUINE ANATOMY, 
Fig. 12. 




ARTERIES OF THE BRAIN. 

Medulla oblongata ; p, Pons Varolii ; l, Mastoid lobule ; o, Olfactory lobule; c, Chiasma 
of the optic nerves; m, Mamillary, or pisiform tubercle; h, Pituitary gland ; three- 
fourths have been excised, i, i, Cerebro-spinal arteries; 2, Median spinal artery; 
3, Lozenge-shaped anastomosis of the two cerebro-spinal arteries, from which result, in 
front, 4, The basilar trunk (usually the cerebro-spinal arteries arrive in the middle of 



CIRCULATORY APPARATUS. 9 1 

Posterior cerebellar, to lateral and posterior borders of cerebellum. 

Anterior cerebellar, two or three in number. To anterior portion 
of cerebellum. 

Two anastomosing branches with internal carotid. They are not 
constant, and unite with carotids at second curvature. 

Posterior cerebral are given off from the basilar terminal branches, 
pass outward and enter Bichat's fissure, where they terminate in the 
choroid plexus or on the surfaces of the cerebrum and cerebellum. 

Median spinal artery passes along the inferior fissure of the cord 
from its beginning to its end. It receives branches from the vertebral, 
intercostal, lumbar and sacral arteries, and supplies the cord and its 
membranes. 

INTERNAL CAROTID. 

Passes up to base of skull through occipito-temporo-sphenoidal 
opening, enters the cavernous sinus, has two curves develop in its 
course; in the second, anastomosing with the basilar. They com- 
municate with each other by a transverse branch, pass forward and 
bifurcate behind the optic tract, into the posterior communicating and 
the common trunk of the anterior and middle cerebrals. 

Posterior com?nunicating passes backward beside the pituitary body 
and unites with the posterior cerebral. 

Middle cerebral passes outward into Sylvian fissure, and supplies 
the brain structure. 

Anterior cerebral passes above optic commissure, unites with its 
fellow, curves around the corpus callosum, runs backward, and sup- 
plies the brain structure. It anastomoses with post-cerebral and 
ophthalmic. 

EXTERNAL CAROTID. 

Passes forward and upward to great branch of hyoid, then ascends 
to neck of condyle of lower jaw, where it bifurcates into the super- 
ficial temporal and internal maxillary. 

the lozenge) ; 5, 5, Posterior cerebellar arteries ; 6, Anterior ditto ; 7, Internal carotid 
artery, with the two curves it makes in the cavernous sinus ; 8, Internal carotid on the 
sides of the pituitary gland; 9, Transverse reticulated anastomosis thrown between the 
two internal carotids behind the pituitary gland ; 10, Bifurcation of the internal carotid ; 

11, 11, Posterior cerebral arteries anastomosing behind the pisiform tubercle, receiving 
in the middle of this anastomosis the two terminal branches of the basilar trunk ; 

12, Middle cerebral artery ; 13, Anterior cerebral artery; 14, Posterior communicating 
artery. 



92 EQUINE ANATOMY. 

Branches. 

A few to the guttural pouch and parotid gland. 

i . G las so-facial or external maxillary. 

Passes downward, forward and upward, outside of lower jaw in 
front of masseter, where it divides, above the maxillary spine, into an 
ascending branch to the nasal muscles, and a descending branch 
to the nasal openings. 

Branches. 

Pharyngeal, to soft palate and pharynx. 

Lingual, to tongue. 

Sublingual, to sublingual gland, fraenum linguae, and buccal mucous 
membrane. 

Inferior labial or coronary, to structures of lower lip, anastomosing 
with opposite. 

Superior labial, to upper lip and nose. 

2. Maxillo-muscular. 

To pterygoid and masseter muscles. 

3. Posterior auricular. 

To external ear, to parotid and middle ear by stylo-mastoid foramen. 

4. Superficial temporal. 

Passes upward a short distance and divides into the anterior auri- 
cular and sub-zygo?natic. The former supplies the external ear, parotid 
gland and temporal muscle ; the latter passes across face forming the 
transverse facial, and ends in the masseter muscle. 

5. Internal maxillary. 

Passes inward along the outer side of the guttural pouch, enters the 
sub-sphenoidal foramen, and orbital hiatus, passes through maxillary 
hiatus to the palatine canal, where it terminates in the palato-labial. 

In the first or buccal part it gives off its first five branches, in its 
second or sphenoidal part two, and four from its third or infra-orbital 
part. 

Branches. 

1. Inferior dental, through inferior dental canal to lower jaw and 
teeth, giving off mental artery at the foramen. 

2. Pterygoid vessels, to muscle. 

3. Tympa7iic, through Glasserian fissure to tympanic cavity. 

4. Spheno-spinous, or great meningeal, through anterior lacerated 
foramen to dura mater. 



CIRCULATORY APPARATUS. 93 

5. Posterior temporal, to muscle. 

6. Deep anterior temporal, to temporal fossa. 

7. Ophthalmic, passes into orbit, then out of it by the orbital 
foramen, and divides in the ethmoidal fossa. It gives off muscular 
and ciliary arteries to the eye, the central artery of the retina, the 
supra-orbital to the forehead, the lachrymal \.o the upper lid and gland, 
cerebral branches to the anterior lobes of the brain and terminates by 
the meningeal branch to the dura and a nasal branch to the ethmoid 
and median septum. 

8. Buccal, to superficial and deep facial muscles. 

9. Staphylin, to soft palate, by posterior palatine groove. 

10. Superior dental, passes through superior dental canal to infra- 
orbital foramen, where it divides into one small branch to the face, 
and another to the incisor, canine and anterior molar teeth. 

11. Nasal, to outer and inner walls of nasal cavity. 
Palato-labial, passes along palatine groove to near central incisors, 

then up through the incisive foramen to the nose and structures of the 
upper lip and gum. 

POSTERIOR AORTA. 

Passes upward and backward to the seventh dorsal vertebra, form- 
ing its arch, thence to the space between the pillars of the diaphragm, 
where it becomes the abdominal aorta. At the last intervertebral 
articulation it ends in a double bifurcation, the two internal and two 
external iliac arteries. 

THORACIC AORTA. 

From seventh dorsal to pillars of diaphragm. 

Branches. 

Intercostals, 17, the first from the cervical, the next three from 
dorsal, and remainder from aorta. Divides into a superior branch to 
muscles, skin and cord, and an inferior or intercostal behind each rib, 
which anastomoses below with internal mammary. 

Bro7icho-cesophageal. 

By two branches to bronchi and lungs, by two to oesophagus, and 
small branches to trachea, glands and mediastinum. 

ABDOMINAL AORTA. 

From diaphragm to bifurcation. 

Branches. 

Phrenic, two or three, to diaphragm. 



Fig. 13. 




CIRCULATORY APPARATUS. 95 

Cceliac axis. 

Below preceding, and divides after one-half of an inch, into gastric, 
hepatic and splenic. 

Gastric, by two branches to stomach, gullet and lung. 

Splenic, passes to left to spleen, and gives off branches to spleen, 
stomach and left gastro-omental. 

Hepatic, passes forward and to right to liver and gives off 

Pancreatic , pyloric a7id right gastro-07tie?ital branches. 

GREAT MESENTERIC. 

Arises near renal vessels two inches behind the preceding, passes 
downward, and after a course of 1% inches divides into branches to 
small intestine, ilio-ccecal, superior and i7iferior cacal, right colic, left 
colic, small colic and some twigs to supra- renal capsules, mesentery, 
etc. 

SMALL MESENTERIC. 

Arises four to six inches behind preceding, and sends branches to 
the small colon and rectum. 

Renal, two. 

Arise near great mesenteric, and supply the kidneys and supra- 
renal glands. 

Spermatic, two in number. 

In the male are called great testicular, in female u tero- ovarian. 
Arise near small mesenteric and pass through inguinal canal to testicle, 
in the female to the ovaries and cornua of the uterus. 

Small testicular, male ; titerine, female. Two in number. 

Arise from bifurcation of aorta or from internal iliacs, to spermatic 
cord in male, and uterus and vagina in female. 

Fig. 13. — DISTRIBUTION OF THE EXTERNAL AND INTERNAL ILIAC ARTERIES IN THE MARE. 

i, Abdominal aorta; 2, Internal iliac artery; 3, Common origin of the internal pudic and 
the umbilical arteries — the latter is cut; 4, Internal pudic artery ; 5, Vaginal artery ; 
6, Lateral sacral artery ; 7, Origin of the gluteal artery, which springs in this instance 
from the lateral sacral, a circumstance most frequently observed in the Ass ; 8, Origin 
of the ilio-muscular artery ; 9, Origin of the ilaco-femoral artery ; 10, Obturator artery; 
11, External iliac artery ; 12, Circumflex iliac artery, cut; 13, Femoral artery; 14, Com- 
mon origin of the deep femoral and pre-pubic arteries ; 15, Origin of the anterior great 
muscular artery; 16, Origin of the saphena artery, cut; 17, Innominate branch; 
18, Popliteal artery; 19, Femoro-popliteal ; 20, Satellite artery of the great femoro- 
popliteal nerve; 21, Posterior tibial artery; 22, Its communicating branch with the 
saphena ; 23, External plantar artery ; 24, Satellite artery of the internal plantar nerve ; 
25, Digital artery. 



g6 EQUINE ANATOMY. 

Lumbar, five or six. 

Divide into superior branch to lumbar muscles, cord, and inferior 
to abdominal and psoas muscles. 

Sacra media. 

A single vessel arising at bifurcation of aorta, passes along inferior 
face of sacrum and gives branches to parts in vicinity. 

INTERNAL ILIAC. 

From aorta to insertion of small psoas dividing into obturator and 
ilio-femoral. 

Umbilical. 

A cord to top of bladder, giving off some vesical branches. 

Internal pudic, to neck of bladder, bulb of urethra, prostate and 
seminal vesicles. In female to vagina and uterus. 

Lateral sacral. 

Passes backward alongside of sacrum, gives off middle and lateral 
coccygeal and ischiatic branches. 

Ilio lumbar, to sacro-iliac joint and muscles. 

Gluteal, emerges from pelvis by great sciatic notch, and supplies 
gluteal muscles. 

Obturator, emerges from pelvis by obturator foramen, and sends 
branches to muscles, bladder and the artery of the corpus cavernosum, 
giving off the posterior dorsal artery of the penis. 

Ilio-femoral. 

Passes out of the pelvis with the iliacus muscle, and ends in the 
muscles of the thigh. 

EXTERNAL ILIAC. 

From end of aorta to Poupart's ligament, where it ends in the 
femoral. The vein lies to the inner side. 

Branches. 

Small testicular. — See before. 

Circumflex iliac, passes outward and divides into an anterior 
branch to the abdominal muscles and a posterior to the iliac muscles 
and skin of thigh. 

FEMORAL. 

From Poupart's ligament to the opening in the great adductor of the 
thigh, where it becomes the popliteal. 

Branches. 

Pre-pubic, lies on anterior face of Poupart's ligament, and divides 



CIRCULATORY APPARATUS. 97 

into the posterior abdominal (epigastric), which passes forward into 
rectus abdominis muscle, anastomosing with the anterior abdominal 
and the external pudic, which passes through the inguinal canal, and 
divides into a subcutaneous vessel on the abdomen and the anterior 
dorsal artery of the penis. In the female this supplies the mammary 
gland. 

Profunda, passes back behind adductors and supplies muscles of 
thigh and coxo-femoral joint. 

Superficial muscular, to anterior crural muscles. 

Small muscular, to muscles, irregular in distribution, one giving off 
the nutrient vessel to femur, the largest in the body. 

Saphena, accompanies the saphena vein to inner side of leg, thigh, 
and back. 

POPLITEAL. 

From opening in adductor magnus, passes beneath the gastrocnemii 
and popliteus, and bifurcates at the tibio-fibular arch after a course of 
eight inches into the anterior and posterior tibials. 

Branches. 

Articular, to femoro-tibial joint. 

Muscular, to muscles of ham ; one follows great femoro-popliteal 
nerve. 

Feinoro-popliteal, passes backward and supplies muscles and nerves. 

POSTERIOR TIBIAL. 

From end of popliteal to side of astragalus, where it divides into 
the two plantar arteries. 

Branches. 

Muscular. 

Tarsal articular. 

Nutrient artery to tibia. 

Plantar, lie along tendon of perforans, and end at the suspensory 
ligament of the fetlock, anastomosing with the perforating pedal ; 
forming an arch which gives off the external and internal plantar 
interosseous, which supply the metatarsal region. 

ANTERIOR TIBIAL. 

Along front of tibia to tibio tarsal joint, where it becomes the pedal. 
It gives off muscular branches and one along fibula, the analogue of 
the peroneal of man. 



98 EQUINE ANATOMY. 

PEDAL. 

Divides opposite the second tarsal row into the perforating pedal, 
which passes between cuboid and scaphoid to anastomose with plan- 
tars and collateral artery of the can?ion. This passes downward, then 
backward between external and middle metatarsus, then down to top 
of fetlock, where it divides into the two collateral arteries of the digits, 
which pass downward to the basilar process of the pedal bone, divid- 
ing into the plantar and pre-plantar ungual. 

Branches. 

To upper bones of digits, joints, tendons, etc. 
To plantar cushion. 

Coronary circle, to structures around os coronae. 
Pre-plan tar f enter foramina in os pedis. 

Plantar, passes into plantar fissure, plantar canal and semilunar 
sinus, uniting with opposite to form the semilunar anastomosis. 

PULMONARY ARTERY. 

Arises from right ventricle, passes upward and backward dividing 
into two branches, which enter the lungs and ramify in them. At its 
middle is a fibrous cord, running to the arch of the aorta, the remains 
of the ductus arteriosus of fcetal life. 

The artery carries venous blood to the lungs for oxygenation. 



THE VEINS. 

The veins carry venous blood from the periphery to the heart, 
except the pulmonary, that carry arterial blood to the left heart. 
They have three coats, an internal serous, middle muscular and 
external fibrous. In the lumen of the veins are valves with their con- 
cavity toward and their convexity away from the heart. They are 
absent in the pulmonary and portal veins and vena cava and very 
large and numerous in the extremities. 

The venae comites are two veins accompanying each small artery; 
the larger arteries have only one. 

Coronary. 

Small branches and great coronary empty into right auricle after 
receiving the bronchial veins. 



CIRCULATORY APPARATUS. 99 

ANTERIOR VENA CAVA. 

A large trunk from anterior opening of thorax to right auricle formed 
by the union of the two axillary and two jugular vessels. 

Branches received. 

Internal thoracic, vertebral, superior cervical and dorsal vein, ac- 
companying the arteries of the same name. 

Great vena azygos, from first lumbar vertebras to sixth dorsal, through 
aortic opening of diaphragm, and enters the anterior cava, often re- 
ceiving the lumbar and aortic intercostals. 

JUGULAR VEINS. 

Begin behind inferior maxilla, below its articulation, by the joining 
of the superficial temporal and internal maxillary. Passes down to 
entrance of chest, the two uniting and forming a confluence, into which 
the axillary veins empty. It is separated, above, from the carotid by 
the omo-hyoid ; in the lower part it is in direct relation to the vessel. 

Branches. 

Maxillo-muscular, posterior auricular, occipital, glos so-facial, thy- 
roid, cephalic ox plat, and many smaller ones. 

SINUSES OF THE DURA MATER. 

Median, from crista galli to torcular Herophili. 
Cavernous, from alveolar vein in front to lacerated foramen behind. 
Occipito-atloid, about base of skull, entering spinal veins. 
Petrosal, from cavernous to sub-sphenoidal conduit, where it empties 
into occipital. 

SPINAL VEINS. 

Median spinal, which gives off branches to the vertebral, intercostal, 
and lumbar veins. 

AXILLARY VEINS. 

Formed by union of subscapular and humeral near scapulo-humeral 
articulation and empty into jugulars. 

VEINS OF ARM. 

Humeral, with artery and deep branches. 
Subscapular, uniting with preceding. 
Subcutaneous thoracic or spur, into humeral. 



* wmii* 



$jm^m 



111 



yP 



41 



0«. 




CIRCULATORY APPARATUS. IOI 

FOREARM. 

^Anterior and posterior radial, ulnar, median ending in basilic, 
cephalic ox plat, and subctctaneous radial. Into these empty the veins 
that accompany the corresponding small arteries of the metacarpal 
and digital regions. 

POSTERIOR CAVA. 
Begins at entrance of pelvis by union of common iliac veins, passes 
forward and to right, grooves liver, through diaphragm, and ends at 
the right auricle of heart. 

Branches. 

Phrenic, 3. 

Portal vein. 

Formed by junction of small mesenteric, great mesenteric and sple7iic, 
similar to the same arteries. It begins near the great mesenteric 
artery, passes through the pancreatic ring, and divides in the great 
posterior fissure of the liver to enter its structure. 



Fig. 14. — GENERAL VIEW OF THE VEINS IN THE HORSE. 

i, Anterior vena cava; 2, 2, Posterior vena cava; 3, Right pelvi-crural trunk, divided at 
the ilio-sacral articulation; 4, Left pelvi-crural trunk; 5, Femoral vein ; 6, Obturator 
vein ; 7, Sub-sacral vein ; 8, Left testicular vein ; 9, Posterior abdominal vein ; 10, Renal 
vein; 11, 11, Ascending branches of the asternal vein ; 12, Vena azygos, with its inter- 
costal branches, and in front the sub-dorsal venous branch, 13; 14, (^Esophageal vein; 
15, Dorsal, or dorso-muscular vein; 16, Cervical, or cervico-muscular vein ; 17, Verte- 
bral vein ; 18, Right axillary vein, cut at the anterior border of the first rib ; 19, Sub- 
sternal, or internal mammary vein ; 20, Left axillary artery; 21, Termination of the 
left cephalic vein; 22, Left jugular; 23, Right jugular; 24, External maxillary, or 
glosso-facial vein ; 25, Coronary vein; 26, Angular vein of the eye; 27, Sub-zygomatic 
vein ; 28, Posterior auricular vein ; 29, Maxillo-muscular vein ; 30, Internal metacarpal 
vein; 31, Median subcutaneous vein; 32, Radial subcutaneous vein; 33, Posterior 
radial vein; 34, Basilic vein ; 35, Plat, or cephalic vein; 36, Coronary venous plexus; 
37, Digital vein; 38, Internal metatarsal vein; 39, Anterior root of the internal saphena 
vein ; 40, Posterior root of ditto ; 41, Internal saphena ; 42, Great coronary vein ; 
43, Small mesaraic vein; 44, Different branches of the great mesaraic vein; 45, Trunk 
of the vena portae in its sub-lumbar portion, lodged in the pancreas; 46, The same in the 
posterior fissure of the liver ; below it is seen entering the substance of the gland. — 
m, Sub-scapular hyoideus muscle cut obliquely in the direction of the trachea; p, Cervi- 
cal panniculus turned down to expose the jugular channel ; o, Right auricle of the 
heart; a, Posterior aorta; g, Section of the right lung; f, Left lobe of the liver behind 
the section of the diaphragm ; r, Right kidney carried up and forward ; l, (Esophagus ; 
v, Bladder; s, Rectum; t, Thoracic duct; T 7 , Termination of that duct in the con- 
fluent of the jugulars. 



102 EQUINE ANATOMY 

The right gastro-epiploic vein and gastric enter the cava near the 
posterior fissure. 

Renal, two, similar to arteries ; left is longer. 

Spermatic \ follow the artery in male or female. 

Lumbar, follow arteries. 

Common iliacs. 

Unite under second lumbar body to form cava. 

The common and external iliacs follow the course of the arteries 
and receive similar branches. 

Femoral vein follows artery, as does the popliteal, anterior and pos- 
terior tibial. 

Internal saphena. 

Superficial in position from metatarsal veins, passes along inner 
side of leg and thigh, and empties into femoral or external pudic. 

External saphena. 

Begins outside calx and ends in popliteal vein. 

Metatarsal. 

Internal, external and middle. 

Digital. 

As in anterior limb. 

PULMONARY VEINS. 

Are four to eight in number and extend from root of lung to the left 
auricle. They carry arterial blood and are destitute of valves. 



LYMPHATICS. 

The lymphatics are vessels with very thin and transparent walls, 
found all over the body except in blood-vessels, nervous tissue, bone, 
muscles, eyeball, cartilage, tendons, the membranes of ovum, placenta, 
umbilical cord, cuticle or hair. They possess nutrient vessels, no 
nerves, have valves, and carry lymph or chyle into the vascular system. 

The lymphatic glands are small ovoid bodies in the course of lymph 
channels; they exist as groups in the sub-lumbar, inguinal, popliteal, 
iliac , femoral , pre-pectoral, pharyngeal, pre-scapular, mcdiasti)ial and 
bronchial regions. 

They have a special capsule and are composed of reticular tissue. 
The lymphatics break up into smaller ones before reaching the gland, 
called the afferent vessels, and are united again on the opposite side 
as the efferent vessels. 



NERVOUS SYSTEM. I03 

THORACIC DUCT. 

Receives all the lymphatics except those of the right side of the 
head, neck, thorax and right anterior limb. Begins at the first lum- 
bar vertebra as a cistern, the " receptacuhim chyli." The duct then 
passes forward through the pillars of the diaphragm to the sixth dor- 
sal vertebra, where it passes to the left and empties, after a dilatation, 
into the anterior cava at the junction of the jugulars. 

RIGHT LYMPHATIC DUCT. 

Opens at junction of jugulars and is guarded by a valve. It is 
about two inches long and receives all the lymphatics that do not 
empty into the great duct. 



NERVOUS SYSTEM. 

This system is divided into the cerebrospinal, presiding over animal 
life, and sympathetic, over organic life. 

It is composed of white fibres, gray vesicles in a stroma of neuroglia 
or connective tissue, and a gelatinous material in the sympathetic. 

The white nervous tissue is composed of an outer envelope or 
ttibitlar membrane , a middle coat called the white substance of Schwann, 
and a central portion which transmits nervous impulses, the axis cylin- 
der. Outside a nerve which comprises a number of the preceding we 
find a covering, the neurilemma: sensory nerves terminate at the pe- 
riphery in many different ways, motor nerves as small plexuses on the 
muscle cells. 

CEREBRO-SPIXAL SYSTEM. 
Consists of the brain, spinal cord, ganglia and nerves. 

SPINAL CORD. 

The portion of the nervous system enclosed in the spinal canal 
and extending from the occipital foramen to the upper third of the 
sacral canal. Its weight is 10^ ounces; it is flattened above and 
below, and has two enlargements in its course, one between the fifth 
cervical and second dorsal, the brachial, the other below, the crural. 

The structure is externally white matter, internally gray, arranged 



io4 



EQUINE ANATOMY. 



like two horns, the larger ends pointing down and out, not reaching 
the surface ; the smaller look upward and outward, reaching the surface. 
The two horns are connected by a transverse band, called the com- 
missure, which shows in its middle the central canal of the cord. 

Fissures. 

Running the whole length of the cord above and below are two 
fissures; the superior longitudinal is narrower and more shallow than 
the inferior, which is separated from \he gray commissure by a white 
band, the wJcite commissure. 

Fig. 15. 




SECTION OF THE SPINAL CORD OF THE HORSE AT THE LUMBAR REGION ; MAGNIFIED TWO 

DIAMETERS. 

i, Superior median fissure; 2, Inferior median fissure; 3, 3, Superior collateral fissures; 
4, 4, Inferior ditto ; 5, Gray commissure ; 6, White commissure ; 7, 7, Superior gray 
cornua ; 8, 8, Inferior gray cornua ; 9, Central canal. 



Columns. 

The superior column lies between the superior fissure and superior 
or sensory nerve roots. 

The inferior, between the inferior fissure and the inferior or motor 
roots. 

The lateral lies between the two. 

Membranes. 

Dura mater, outer, is not adherent to bony canal. 

Arachnoid, as in brain. 



NERVOUS SYSTEM, I05 

Pia mater, passes into fissures and on sides has festoons attached to 
the dura, the ligamentum dentata. Its posterior extremity forms a 
narrow prolongation the Jiium terminate. 

BRAIN. 

This is the central portion of the nervous system, situated in the 
cranial cavity. 

Membranes. 

The dura mater, externally is a strong fibrous membrane, adherent 
to the bony walls, giving off prolongations into the brain and forming 
depressions for the venous sinuses (see Veins). It also is prolonged on 
the nerves. The prolongation of the dura are the (A) fatx cerebri, 
passing between the two hemispheres of the brain and attached to the 
crista galli. It contains in its meshes small tubercles, the pacchionian 
bodies. 

(B) Tentorium cerebetti, which forms a horizontal partition between 
the cerebrum and cerebellum, and attached to the parieto-temporal 
crest, and parietal protuberance. 

(C) Pituitary fold, circumscribes the sctta turcica and envelops the 
pituitary gland. 

The arachnoid is the middle membrane, composed of a basement 
membrane, attached to the dura externally and a covering of flattened 
endothelium internally. It is not properly a vascular membrane. It 
does not pass into the fissures or convolutions, and between it and the 
pia is a space filled with cerebro-spinal fluid, the sub-arachnoid space. 

Pia mater. 

The most internal of the membranes ; is of thin structure, holding 
in its meshes a large number of blood-vessels which have peri-vascu- 
lar lymph spaces about them. The pia passes into all the inequalities 
of the surface of the brain, and supplies it with blood. 

Weight. 

In the horse, 22 ounces, 15 drachms*; ox, 16 ounces, 15 drachms. 

In human male, 49^ ounces. 

Parts of the brain. 

Cerebrum, or large brain ; cerebettum, or small brain ; the isthmus 
and medulla oblongata. 

Medulla Oblongata. 

The medulla is the upper expanded portion of the cord, ending 
8 



lo6 EQUINE ANATOMY. 

at the pons, and rests on the basilar process. It shows the superior 
median and inferior median fissures, the latter separating to form the 
fourth ventricle, the point of divergence being called the calamus 
scrip tor ius. 

Columns. 

The inferior median columns are continued as the pyramids ; out- 
side these are two oblong elevations (the olivary bodies of man), in 
front of which arise the sixth, and behind, the twelfth nerves. 

The superior median column is continued in the medulla as the 
restiform body. 

The lateral tracts are the continuation of the lateral columns. 

The Isthmus 

Is the prolongation of the medulla, supporting the cerebellum, and 
terminating in the cerebrum. Its component parts are the pons varolii 
or mesencephalon , crura cerebri and cerebelli, valve of Vieussens, cor- 
pora quadrigemina, thai ami optici, pineal and pituitary glands. 

Pons varolii. 

The pons is an elevated mass of white transverse fibres thrown 
between the two halves of the cerebellum ; it rests in a depression on 
the basilar process, and below presents a longitudinal median groove 
for the basilar artery (see Arteries). The crura pass above it. 

Crura cerebri. 

The crura are two white bands continuous with the fibres of the 
medulla, entering the hemispheres of the cerebrum in front, and in 
contact with the optic thalami and quadrate bodies above, the pons 
below. In front they pass under the optic tracts, which here unite 
and form the optic commissure. The crura also separate anteriorly 
to enclose the corpus albicans. 

Crura cerebelli. 

The cerebellar crura are composed of three fasciculi : — 

i. Cms cerebelli ad fiontem-r-the pons' transverse fibres. 

2. Cms ad medullam — the restiform bodies of the medulla. 

3. Processus e cerebello ad testes ; or anterior crura to the testes ot 
the corpora quadrigemina. 

The valve of Vieussens is a thin, transverse layer, which passes 
between the anterior cerebellar crura. It forms part of the roof of 
the fourth ventricle. 

The corpora quadrigemina are four small bodies which lie above 



NERVOUS SYSTEM. \OJ 

the crura cerebri ; the anterior pair, or the nates, are gray ; the 
posterior, or testes, are white. 

The optic thalami are two masses of gray matter placed above the 
crura cerebri ; they are separated by a deep groove, and form the 
sides of the third ventricle. At their posterior border are found two 
projections, the external and internal geniculate bodies. 

The pineal gland or conarium is a cone-shaped body, of a reddish 
brown color, situated in front of the testes, with two peduncles pass- 
ing forward on the inner sides of the optic thalami. It is composed 
of amorphous tissue, holding salts of lime, etc. 

The pituitary gland is a small, circular body attached by the 
infundibulum to the tuber cinereum, a layer of gray matter in the floor 
of the third ventricle. It has no cavity or definite structure. (For 
interior of isthmus see Ventricles^) 

Cerebellum. 

The cerebellum is that part of the brain situated behind and beneath 
the cerebrum, above the isthmus and separated from the cerebrum by 
the tentorium. 

It is divided into three lobes by a median constriction, which is 
divided into the superior and inferior vermiform processes. 

The lateral lobes are convex, and show many convolutions or de- 
pressions. 

Structure. 

Gray externally, white internally, with a tree-like arrangement 
called the arbor vitce. 

Cerebrum. 

The cerebrum is composed of two portions, the hemispheres elon- 
gated antero-posteriorly, separated by a deep fissure running in the 
same direction and united by a transverse commissure — the corpus 
callosum. 

The longitudinal fissure. 

This passes antero-posteriorly, separating the two hemispheres, and 
bounded below by the corpus callosum. Behind, at the anterior and 
superior portion of the medulla it changes its direction, transmits the 
velum interpositum, and is called the fissure of Bichat or transverse 
fissure. The longitudinal fissure lodges vessels and the falx cerebri. 

The fissure of Sylvius is a transverse depression in front of the 
mastoid lobule, lodging the middle cerebral artery. 



io8 



EQUINE ANATOMY. 



Lobes. 

The olfactory or ethmoid is a detached portion lying below and in 
front of the anterior portion of the cerebrum. It arises by two roots, 



Fig. 16. 




GENERAL VIEW OF THE BRAIN; LOWER SURFACE. 

Olfactory lobe ; 2, Cavity of the olfactory lobe ; 3, External root of the olfactory lobe; 
4, 5, Cerebral hemispheres ; 6, Cerebellum ; 7, Optic chiasma, or commissure ; 8, Pitui- 
tary gland ; 9, Optic nerves ; 10, Tuber cinereum ; n, Crus cerebri; 12, Third cranial 
nerve; 13, Fourth nerve ; 14, Pons Varolii ; 15, Fifth nerve; 16, Sixth nerve; i7,Seventh 
and eighth nerves; 18, Medulla oblongata, the number being placed on the olivary 
body; 19, Anterior pyramid ; 20, Roots of ninth, tenth, and eleventh nerves ; 21, Twelfth 
nerve. 



one from the outside of the mastoid lobe and one near the optic chiasm. 
The enlargement or bulb lies on the ethmoidal fossa, and has an internal 
cavity communicating with the lateral ventricle (see First Nerve), 



NERVOUS SYSTEM. IO9 

Mastoid or sphenoid lobe represents the middle lobe of man ; its 
margins form the transverse fissure and fissure of Sylvius. Its interior 
forms a cavity, the reflected portion of the lateral ventricles. The 
convolutions of the brain are numerous and distinct, but do not call 
for a detailed description. 

INTERIOR OF THE BRAIN. 

The corpus callosum is the transverse commissure between the 
hemispheres and seen on separating them. On its top are seen the 
nerves of Lancisi running in its long axis. Its i?iferior surface forms 
the roof of the lateral ventricles separated by the septum lucidum. 
Its sides end in the interior of the hemispheres. Its hinder border 
forms the splenium (or pad), turns forward as the genu (or knee), and 
is continuous with tlje fornix. Its anterior portio?i ends in the cerebral 
substance. 

THE VENTRICLES. 

These are cavities in the interior of the brain as follows — 

Lateral Ve7itricles (two), below the callosum. 

Third J entricle, between the thalami optici. 

Fourth Ve?itricle, between the diverging restiform bodies of medulla. 
(The cavity between the lamellae of the septum lucidum, ihe fifth ven- 
tricle of man, is absent in the horse.) 

LATERAL VENTRICLES 

Are lined by a serous membrane, the " ependyma," and bounded — 

Above, by corpus callosum. 

Below, by corpus striatum, fornix, hippocampus, and choroid plexus. 

Internally, by septum lucidum. 

Externally, by brain structure. 

Anteriorly, continued into cavity of olfactory lobe. 

Posteriorly, continued downward and upward into the mastoid 
lobe. 

It communicates below and in front by two openings, the foramina 
of Monro, with the third ventricle. 

The septum lucidum is a thin partition of white matter between the 
lateral ventricles. 

The fornix, a single body between the third and lateral ventricles, 
is continuous behind with the callosum. It is composed of white 
matter, terminating behind in two prolongations the posterior pillars, 
ending in the hippocampus, in front by two similar ones, which form 



IIO EQUINE ANATOMY. 

the corpus albicans. They form the anterior boundaries of the fora- 
mina of Monro, 

The hippocampi are nuclei of gray, covered with white matter on 
the floor of the lateral ventricle. They are formed by the bending in 
of the convolution above the corpus callosum and present a flattened 
border, the corpus jimbrialum. 

The corpora striati are projections on the floor of the lateral ven- 
tricles, of gray and white tissue in lamellae. They are separated from 
the thalami by long bands, the tcEnice semicirculares. They are divided 
into two parts, the intra-ventricular and extra-ventricular nuclei. 

The choroid plexus is a process of the pia that passes in by the great 
transverse fissure, becomes the velum interpositum, passes from the 
lateral to the third ventricle and beneath the fornix. Their veins 
form the vence galeni, which end in the sinus of the falx. 

THE THIRD, OR VENTRICLE OF THE THALAMI OPTICI. 

Boundaries. 

Roof, optic thalami meet together. 

Floor, lamina cinerea. 

Sides, optic thalami and peduncles of pineal gland. 

Communications. 

In Front, foramen of Monro with lateral ventricles. 

BeMnd, the iter a tertio ad quartum ventriculum, or aqueduct of 
Sylvius, passing under the corpora quadrigemina to end in the fourth 
ventricle. 

Running across the cavity are also seen the anterior white commis- 
sure between the corpora striata, and the posterior white commissure 
between the thalami, behind. The gray commissure, is simply the 
coming together of the thalami forming the roof. 

THE FOURTH, OR CEREBELLAR VENTRICLE (see Medulla). 

Boundaries. 

Roof, valve of Vieussens and cerebellum. 

Floor, medulla and pons. 

Sides, restiform body and processus e cerebello ad medullam. 

Anteriorly, continuous with aqueduct of Sylvius. 

Posteriorly, summit of calamus scriptorius. 



NERVOUS SYSTEM. Ill 

S true Hire of the Brain. 

Gray structure externally and dipping down into the convolutions. 
There are seven layers in the cortical substance (Kolliker). 

The white substance is found internally and runs, as fibres, in vari- 
ous directions. 

THE CRANIAL NERVES. 

They are twelve in number (Sommering). 

1st, or Olfactory. Nerve of smell (see Smell). 

Superficial Origin. — See Olfactory lobe. 

Deep Origin. — Corpus striatum and transverse fibres of pons. 

Exit. — Through cribriform plate of ethmoid. 

Distribution. — To nasal septum and ethmoidal cells in upper third 
of nasal fossae. 

Function. — Well marked and presides over sense of smell. 

2d, or Optic. 

Origin. — From commissure and optic tracts which arise from thala- 
mus and corpora quadrigemina. 
Exit. — Optic foramen. 
Distribution. — To retina (see Eye). 
Function. — Xerve of sight. 

3d, or Oculo-motor. 

Superficial Origin. — From crura near interpeduncular fissure. 

Deep Origin. — Anterior border of pons. 

Exit. — Smallest supra-sphenoidal foramen of orbit. 

Distribution. — To all muscles of eye except external rectus, great 
oblique and part of the posterior rectus, and by ophthalmic ganglion 
to the iris. 

4th, or Patheticus. 

Superficial Origin. — Band of Reil behind corpora quadrigemina. 
Deep Origin. — From interior of isthmus. 
Exit. — By smallest supra-sphenoidal foramen to orbit. 
Distribution. — To great oblique muscle. 

5th, or Trifacial. 

Superficial Origin. — By two roots, the larger, or sensory, from the 
sides of the pons, the motor from pons, near the other. 

Deep Origin. — Sensory root from restiform body of medulla, the 
interior cells of the isthmus and nuclei of other nerves. Motor root 
from antero-lateral fasciculus of medulla. 



112 EQUINE ANATOMY. 

Course, — Has a large ganglion developed on the sensory root, the 
Gasserian, resting on the cartilage of the occipito-spheno-temporal 
hiatus, and divides into the (i) ophthalmic, (2) superior maxillary 
and (3) inferior maxillary divisions. 

Exit. — The first branch passes through the smallest of the large 
supra-sphenoidal foramina to the orbit. The second passes through 
the foramen rotundum to the orbit. The third passes through the 
foramen ovale to the temporo-maxillary articulation. 

1 . Ophthalmic Nerve. — To skin of forehead, eyelid, lachrymal gland 
and nasal fossa. 

2. Superior Maxillary . — Passes along infra-orbital canal, where it 
ends in small branches to the face and upper lip. It sends branches 
to the eyeball, palate, nose and teeth of the upper jaw. 

3. Inferior Maxillary. — The motor root unites with this, passes 
down, enters inferior dental canal, supplies the muscles of mastica- 
tion, teeth of lower jaw. 

Branches Are — 

Muscular ; superficial, temporal, gustatory , to tongue, mylo-hyoid 'and 
7nental. 

Sympathetic Ganglia of Fifth. 

OPHTHALMIC OR CILIARY. 

Situation. — Near nerve to inferior oblique muscle of orbit. 

Motor Root. — From third. 

Sensory Root. — Nasal branch of ophthalmic. 

Sympathetic Root. — Cavernous plexus. 

Distribution. — Ciliary nerves to iris. 

SPHENO-PALATINE OR MECKEL'S. 

Situation. — In space between orbit and foramen rotundum. 

Motor Root. — Vidian nerve of seventh. 

Sensory Root. — Superior maxillary. 

Sympathetic Root. — Cavernous plexus by Vidian. 

Distribution. — To orbit and palate. 

otic or Arnold's. 
Situation. — Near origin of inferior maxillary nerve and Eustachian 
tube. 

Motor Root. — Small petrosal from seventh. 



NERVOUS SYSTEM. II3 

Sensory Root. — Buccal nerve. 

Sympathetic Root. — From plexus on inferior maxillary artery. 
Distribution. — To tensor palati, tensor tympani, Eustachian tube 
and pterygoid muscles. 

6th, or Abducens. 

Superficial Origin-. — From medulla, behind pons. 

Deep Origin. — From inferior pyramid and lateral tract of medulla. 

Exit. — With ophthalmic branch of fifth. 

Distribution. — To external rectus muscle of eye. 

7th, or Facial. 

Superficial Origin. — From medulla, behind pons. 

Deep Origi?t. — Floor of fourth ventricle. 

Exit. — Through internal auditory meatus with eighth ; enters the 
aqueduct of Fallopius; has a ganglion developed on it, the genicu- 
late ; passes out of the stylo-mastoid foramen to the muscles of face 
and subcutaneous of neck. 

Branches. 

Great petrosal, to Meckel's ganglion. 
Small petrosal, to otic. 
Tympanic, to stapedius. 
Chorda tympa7ii, to tongue and mouth. 

Muscular, to occipito-styloid, digastric, stylo-hyoid and subcutaneous 
muscle of neck. 

Auricular, to ear and face. 

8th, or Auditory. 

Superficial Origin. — Restiform body. 

Deep Origin. — Below seventh. 

Exit. — With seventh, by cochlear and vestibular branches to ear. 

9th, or Glosso-pharyngeal. 

Superficial Origin. — Medulla, below eighth. 
Deep Origin. — Floor of fourth ventricle. 

Exit. — By posterior foramen lacerum to back part of tongue and 
pharynx. 

Branches. 

Jacobson s ?ierve (tympanic), carotid, 
Co7n?nunicating with sympathetic, pharyngeal. 



114 EQUINE ANATOMY. 

10th, or Pneumogastric. 

Superficial Origin. — Antero-lateral tract of medulla. 
Deep Origin. — Floor of fourth ventricle. 

Exit. — By posterior lacerated foramen, above carotid artery, to 
front of thorax, dividing into bronchial and oesophageal. 

Branches. 

Communicating to eleventh, superior and inferior cervical ganglia. 
Superior laryngeal, to mucous membrane of larynx and crico- 
thyroid muscle. 

Inferior laryngeal, to all muscles of larynx except crico-thyroid. 

Bronchial, to bronchi and lungs. 

(Esophageal, to oesophagus, stomach, liver and solar plexus. 

11th, or Spinal Accessory. 

Superficial Origin. — Lateral tract of medulla, along whole cervical 
region of cord. 

Deep Origin. — Fourth ventricle. 

Exit. — Up through foramen magnum and foramen lacerum to neck, 
and follows mastoideo-humeralis. 

Branches. 

To cervical sympathetic , sterno-maxillaris, mastoideo-humeralis, cet - 
vical and dorsal trapezius and cervical nerves. 

12th, or Hypoglossal. 

Superficial Origin. — Side of medulla near inferior spinal roots. 
Deep Origin. — From fourth ventricle. 
Exit. — Condyloid foramen. 

Branches. 

To muscles of tongue. 

SPINAL NERVES. 

They are 42 or 43 pairs that leave the spinal canal by the inter- 
vertebral foramina. The superior or sensory roots have a ganglion 
developed on them. The motor and sensory roots unite and soon 
after divide into a superior branch to the spinal muscles and integu- 
ment, and an inferior to the lower part of the trunk and extremities. 
Their relative number in the different regions are — cervical, 8 ; dorsal, 
18 ; lumbar, 6 ; sacral, 5 ; coccygeal, 6 or 7. 



NERVOUS SYSTEM. 1 1 5 

CERVICAL NERVES. 

Eight in number. Divide into superior branches which anastomose 
freely, forming the deep cervical plexus, and send filaments to muscles, 
nerves and integument of sides and top of neck. The inferior 
branches supply the structures on the under side of the neck, forming 
the superficial cervical plexus, and the sixth, seventh and eighth form 
a portion of the brachial plexus. 

Branches. 

Phrenic nerves, from the fifth and sixth cervical, and branch 
from the brachial plexus, pass down inside thorax to front of dia- 
phragm, which they supply. 

BRACHIAL PLEXUS. 

A large fasciculus of nerves which supply the anterior limb and 
anterior portion of the chest and neck. 

Formation. — By inferior branches of sixth, seventh and eighth cer- 
vical and first two dorsal nerves, which unite and subdivide opposite 
the scapulo-humeral joint into branches to the thorax and anterior 
extremity. 

Branches. 

Muscular, to angularis scapulce, rhomboideus, latissimus dorsi, teres 
major, subscapulars. 

Superior thoracic (or external respiratory of Bell), to serratus mag- 
nus. 

Pectoral or i?iferior thoracic, to superficial and deep pectorals. 

Subcutaiieous thoracic, follows spur vein and supplies panniculus 
carnosus and subcutaneous muscle of neck. 

Circumflex, to abductors of limb, teres major, levator humeri, shoul- 
der-joint and integument about shoulder. 

Super-scapular, from sixth and seventh cervical to antea- and postea- 
spinati. 

Musculo-cutaneous, from seventh and eighth, crosses axillary artery, 
passes down front of arm between two insertions of coraco-humeralis, 
supplying it and the coraco-radialis. 

Radial (largest branch of plexus), passes down parallel with 
humeral artery, follows short flexor of forearm and radial artery to 
oblique extensor of metacarpus. 



u6 



EQUINE ANATOMY. 
Fig 17. 




NERVOUS SYSTEM. 117 

Branches. 

To extensors of forearm, metacarpus and digit, and external flexor 
of metacarpus, and sensation to integument of anti-brachial region. 

Ulnar, passes down behind humeral artery to inner side of elbow, 
follows oblique flexor of metacarpus to pisiform bone, where it divides 
into the cutaneous to skin of antibrachial, carpal and external meta- 
carpal regions and external plantar. It gives off branches in its 
course to long extensor of forearm and pectorali, to all muscles of 
posterior brachial region, except external and internal flexors of 
metacarpus. 

Median, arises from posterior part of plexus and a branch from 
musculo-cutaneous, passes down in front of humeral artery, along 
inner side of forearm, then lies anteriorly again and bifurcates at lower 
one-third of forearm into external and internal plantar. 

Branches. 

To flexors of forearm and subcutaneous region of forearm. The 
plantars give off the anterior, middle and posterior digital at the fet- 
lock, which supply the phalangeal region. 

LUMBOSACRAL PLEXUS. 

Formed by last two lumbar and first three sacral nerves. Divided 
into an anterior division lying under the psoas parvus, and a posterior 
behind the internal iliac artery. The a7iterior is formed by the last 
two lumbar, and gives off ilio-niuscular to iliacus muscle. 

Crural or anterior femoral, to muscles of thigh, and by saphe?ious 
branches to skin of inner side of thigh and leg. 

Obturator, passes out of oval foramen to adductors of thigh, pecti- 
neus, short adductor of leg and obturator externus. 

The posterior is formed by first three sacral, and gives off small 
sciatic, which emerges from great ischiatic notch and divides into 
anterior gluteal, to ihiddle and small glutei, tensor vaginal femoris, 



Fig. 17.— NERVES OF THE DIGIT. 

p, Plantar nerve ; b, Median branch ; c, Anterior branch ; d, Digital artery ; h, Inconstant 
division given off to the cartilaginous bulbs ; 1, 1, Branch to the plantar cushion ; 
k, Transverse coronary branch; if, Podophyllous branch; o, Pre-plantar branch ; 
q, Descending ramuscule to the fissure of the patilobes ; r, Ramuscules accompanying the 
digital artery in the plantar fissure ; v, Vein whose presence is not constant, and which 
sometimes accompanies the plantar nerve throughout its phalangeal course. 



Il8 EQUINE ANATOMY. 

and posterior gluteal to glutei, triceps cruris and sensation to posterior 
part of thigh. 

Great sciatic emerges from great sciatic opening, passes along pos- 
terior part of thigh on adductors, between two heads of gastrocnemii, 
along inner side of hock, and ends in external and internal 
plantars. 

Branches. 

Muscular to obturator interims, gemelli, quadrat us femoris, triceps 
cruris, semi-tendinosus, setni-membranosus , great adductor of thigh, 
and posterior tibial muscles. 

External popliteal arises near gemelli muscles, passes downward 
and outward to upper part of leg, where it terminates in the musculo- 
cutaneous, which supplies the extensors of the phalanges and skin of 
metatarsal region and anterior tibial, which lies to outer side of artery, 
giving off muscular and cutaneous branches. 

Branch. 

Peroneal-cutaneous , with external saphenous vein to skin of leg. 
Plantar nerves pass to outer and inner sides of metatarsus, and are 
distributed like the analogous structures in the anterior foot. 

DORSAL NERVES. 

Divide into superior branches, which supply skin and muscles of 
spinal region, and inferior, which send branches down into the inter- 
costal spaces to muscles of chest, by first seven pairs, and muscles 
and skin of abdomen by remainder. In the middle of their course 
they give off a cutaneous branch, which supplies the skin and cu- 
taneous muscles. The first and second form part of the brachial 
plexus. 

THE SYMPATHETIC NERVOUS SYSTEM. 

This consists of two long cords lying under the spinal column, from 
the head to the tail, probably ending in a ganglion under the coccygeal 
vertebrae. 

In its course are many ganglia, which are composed of the gelati- 
nous fibres of Remak, and send branches to the cerebro-spinal system, 
viscera and blood-vessels, forming the vasomotor system. 

The system is divided into cephalic, cervical, dorsal, lumbar and 
sacral portions. 



NERVOUS SYSTEM. II9 

Cephalic consists of three ganglia of fifth nerve (see same). 
Cervical, two ganglia. 

1. One Superior, lying in front of atlas, on carotid. 

Branches. 

Communic citing, to ninth, tenth, eleventh and twelfth nerves, and 
first cervical. 

Carotid, on internal carotid, also to cavernous sinus, Vidian nerve 
and cephalic ganglia. 

Inferior carotid, to external carotid, gutteral pouch, salivary glands 
and pharynx. 

2. One Inferior, near insertion of scaleni on first rib. 
Communicating, to tenth and cervical nerves. 

Cardiac nerves, 5 ; two from left and three from right, to heart, 
bronchi and lungs. 

Dorsal consists of 17 ganglia, below vertebro-costal joints. 

Branches. 

Small ones to chest and pleura. 

Great splanchnic. 

From sixth to fifteenth, to abdomen through arch of psoas parvus, 
and near cceliac axis, and ends in solar plexus, which sends branches 
to stomach, liver, spleen, intestine, kidneys and their capsules. 

Lesser splanchnic. 

From fifteenth, sixteenth and seventeenth, to solar plexus, to kidney 
and supra-renal bodies. 

Lumbar, six in number, lie on psoas parvus. 

Branches. 

Posterior mesenteric plexus, to small colon and rectum. 
Spermatic plexus, to spermatic vessels. 
Pelvic plexus, to pelvic viscera. 

Sacral, four in number beneath sacrum. Small branches to sacral 
region and vessels. 



120 EQUINE ANATOMY. 



VISCERAL ANATOMY. 



DIGESTIVE SYSTEM. 

The digestive system is that part in which the great processes of 
digestion and absorption take place as well as the expulsion of the 
residue after the latter. 

The parts included are named from before, backward, the mouth t 
pharynx and cesophagus, that carry the food to the abdominal organs, 
the stomach and intestines. 

The annexed organs are the salivary glands to the mouth, the liver 
and pancreas to the intestines. 

THE MOUTH. 

The mouth is a cavity between the two jaws, and having an anterior 
opening between the lips and a posterior, the soft palate separating it 
from the pharynx. On the sides are the cheeks ; below, the tongue. 

Tongue. 

This is a flattened muscular organ, elongated antero-posteriorly 
and fixed to the hyoid and inferior maxilla. It presents calyciform 
papillcE on the dorsum near the base, arranged in a V shape. At 
the apex of this are two depressions, the foramina cceca. Filiform 
papillce at middle of dorsum of tongue. Fungiform papillce, club- 
shaped, on posterior yj, of dorsum. A fibrous cord (the cartilage of 
the tongue), 3 or 4 inches long, under the mucous membrane. • 

Muscles. 

Intrinsic, of vertical, longitudinal and transverse fibres. Extrinsic, 
see stylo-glossus, hyo-glossus, genio-glossus and hyo-glossus minimus. 
Action. — See Deglutition. 
Nerves. — Lingual, ninth and twelfth. 
Blood Supply. — Lingual and sublingual. 

Palate. 

See Muscles. 

Blood Supply. — Ascending pharyngeal and internal maxillary. 
Nerves. — From superior maxillary and Meckel's ganglion of the 
fifth. 

Teeth. 

They are passive agents in mastication, and are in number 40 in 



VISCERAL ANATOMY. 121 

the male, 36 in the female — viz., in each jaw 6 incisors, 12 molars, in 
male two canines in addition. 

Parts. 

Crown, fang, neck and dental pulp. 

Structure. 

Ivory or dentine, outside of pulp cavity. 

Cement, covering the dentine. 

Enamel, covers free portion of tooth, formed of small rods. 

Incisors. 

Are pyramidal, flattened from before, backward, with a single fang; 

Fig. 18. 




4 

PROFILE OF THE UPPER TEETH OF THE HORSE, MOKE ESPECIALLY INTENDED TO SHOW THE 
MOLARS J THE FANGS HAVE BEEN EXPOSED. 

a, Molar teeth; b, Supplementary molar; c, Tusk ; d, Incisors. 

they are called in each half of a jaw, the pincer, intermediate and 
lateral from within outward. 

Canines, fangs or tusks. 

Found only in male, between the incisors and molars, the space 
between them and the latter is called the bar. They are pointed, 
have a single fang and grow but once. 

Molars. 

The crowns are flattened and undulated, and communicate with the 
interior of the fangs, which are at first hollow, then filled with dentine. 

The fangs are three in number ; in the terminal molars, both above 
and below, the intermediate four in the upper and two in the lower. 
9 



122 EQUINE ANATOMY. 

SALIVARY GLANDS. 

These secrete saliva, which exerts a chemical and mechanical action 
on the food in the mouth, into which the secretion is poured. 

They are the parotid, sub-maxillary, sublingual, molar, labial, 
lingual and palatine. 

The parotid lies behind the angle of the lower jaw, is the largest, 
and its duct (Steno's) opens opposite the third upper molar. 

The sub-maxillary, lies in the intermaxillary space outside the 
larynx, its duct (Wharton's) opens at the side of the fraenum on a 
small tubercle, the barb. 

The subli?igual lies in the intermaxillary space, under the tongue, 
its ducts (of Rivinian), 15 to 20, open near that of Wharton on a 
ridge. 

The molar are two on each side opposite the molar teeth. 

PHARYNX. 

The pharynx is an elongated cavity behind and above the mouth 
and nasal cavities. 

Coats. 

Muscular, see Muscles. 

Mucous of basement membrane, covered above with ciliated and 
below with flattened epithelium. 

Openings, 7. 

In front two posterior nares, two Eustachian tubes, and isthmus of 
the fauces. 

Below, the tops of the oesophagus and larynx. 
Vessels. — Pharyngeal and thyroidal arteries. 
Nerves. — Ninth, tenth and sympathetic. 

m 

CESOPHAGUS. 

The oesophagus is a long, narrow muscular canal beginning at the 
pharynx, passes through the thorax, deviating to the left, channels the 
lungs, passes through a special opening in the diaphragm, and ends 
in the cardiac extremity of the stomach. 

Coats. 

Muscular. — Superficial, longitudinal and deep circular fibres, the 
upper half are striped, the remainder unstriped. 



VISCERAL ANATOMY. 



Mucous. — Has flattened epithelium and is thrown into numerous 
and marked folds. 

Blood Supply. — External carotid, bronchial and oesophageal. 
Nerve Supply. — Tenth. 



ABDOMINAL CAVITY. 

The abdomen is that part of the great cavity of the trunk behind 
the diaphragm. It is bounded above by the lumbar and sacral verte- 
brae, laterally and below by the abdominal muscles, behind by the 
pelvic brim. 

Regions. 

(a) Superior or sub-lumbar, under the psoas muscles and lumbar 
vertebrae. 

(b) Inferior, from xiphoid cartilage to pubes, and includes recti 
muscles laterally. It is divided from before, backward, into the supra- 
sternal, umbilical and pre-pubic regions. 

(c) Inguinal, about inguinal canals. 

(d) Lateral, from ribs to pelvis, and superior border of small oblique 
to outer border of rectus. The hypochondrium is that part behind 
the costal free borders. The flank is that part covered by the internal 
oblique. 

(e) Diaphragmatic is the space included in the concavity of the 
diaphragm. 

(/) Pelvic, bounded above by sacrum, below by pubes, ischium, 
and obturator internus, laterally by the os innominata and sacro- 
ischiatic ligaments. Behind are placed the rectum and genito-urinary 



STOMACH. 

The stomach is a muscular organ, situated in the diaphragmatic 
region, in whose cavity the principal acts of digestion take place. Its 
capacity is 3 to 3% gallons, its weight 3 or 4 pounds. In form it is 
elongated, often constricted in the middle, and presents an anterior 
and posterior face, a great curvature below, to which is attached the 
great omentum, a lesser curvature, to which is attached the gastro- 
hepatic omentum ; a left dilatation, the fundus, a cardiac extremity 



124 



EQUINE ANATOMY. 



continuous with the gullet, and a pyloric extremity, forming a species 
of valve opening into the duodenum. 

Coats. 

Serous. — Most external, from the peritoneum, and completely cover- 
ing the viscus, except at the greater and lesser curvatures. It has 



Fig. 19. 




STOMACH OF THE HORSE. 

a, Cardiac extremity of the oesophagus ; b, Pyloric ring. 

three folds derived from it, the cardiac from the cardia to the 
diaphragm, the gastro-hepatic from lesser curvature to transverse 
fissure of liver, and the great or gastro-colic omentum from great 
curvature to sub-lflmbar region, end of large and beginning of 
small colon. 



VISCERAL ANATOMY. 1 25 

Muscular. — Three layers, external, over right sac and also left one, 
middle, circular over whole organ, aggregated at the pyloric orifice 
to form the pyloric valve ; internal, looped around left sac. 

Mucous. — This is thrown into folds in the right, but not in the 
left sac. It has a muscular layer, the niuscularis mucosa, and is 
covered with flattened epithelium in the left and cylindrical in the 
right sac. 

Glands. 

Infrequent on left side and like those of oesophagus. Common on 
right sac, and ai;e of two varieties. 

(a) Peptic, with a narrow neck opening into two or three cul-de-sacs, 
lined with rounded epithelium at the periphery and small cells next 
to the lumen. The neck is lined with cylindrical cells. 

{b) Mucous, similar in structure, but the whole gland is lined with 
cylindrical epithelium. 

Blood Supply. — Gastric, splenic, pyloric, oesophageal, right and 
left gastro-epiploic vessels. 

Nerves. — Tenth and solar plexus. 

Intestines. 
The terminal portion of the alimentary system, beginning at the 
pylorus, ending at the anus by the rectum. It is a narrow tube twisted 
and curved upon itself, and divided into small and large divisions. 
Their entire length is about 98 feet — 72 feet for the small and 26 for 
the large. 

SMALL INTESTINES. 

These begin at the pylorus, form a loop over the base of the caecum, 
turns transversely to the left, then form numerous folds, being sus- 
pended by a process of peritoneum, the mesentery, finally terminating 
in the caecum at the right hypochondrium. 

Length, 24 yards ; diameter, 1-1^ inches. 

Divisions. — Duodenum, the first curved portion. 
Jejunum (empty), the greater part. 
Ileum (twisted), the terminal portion. 

Coats, from without inward, are — 

Serous, from peritoneum, covering all the small intestine com- 
pletely, except a portion of the duodenum. 



126 



EQUINE ANATOMY. 




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VISCERAL ANATOMY. 12J 

Mucous. — Soft and covered with columnar epithelium. 
Blood Supply. — Great mesenteric and cceliac axis. 
Nerves. — From solar plexus. 

LARGE INTESTINE. 

Twenty-six feet in length, and consists of the c cecum, large colon, 
small ox floating colon, and rectum. 

Cecum. 

An elongated sac, three feet in length, with a capacity of 7^ gallons, 
lying in the right hypochondrium. Its superior extremity (or crook) 
lies under the right kidney, and shows the two openings of the ileum 
and beginning of the colon ; it is encircled by the curve of the duo- 
denum. 

Coats. 

Serous, from peritoneum. 

Muscular, four external longitudinal layers, which are inserted into 
the circular, forming a number of transverse folds. 

Mucous, thicker than small intestine ; it contains no Bruttnerian 
glands or patches of Peyer. 

Muscular, of non-striated fibres, an external longitudinal, and 
internal circular coat. 

Points of Interest. 

Valvules comiiventes, folds of mucous membrane with fibrous tissue 
between, in duodenal portion, to retard passage of food. 

Openings of bile and pancreatic ducts, or a common orifice, five to 
eight inches from pylorus, and a separate one for the accessory pan- 
creatic duct. 

Villi, elevations which allow of passage of food principles in absorp- 
tion, connected with lacteals. 

Briimier s glands, found in the duodenum; are racemose in char- 
acter, with a short duct. They secrete intestinal juice. 

Crypts of Lieberkiihn, over all parts of membrane; are simply de- 
pressions lined with columnar epithelium. 

Solitary glands are lymphoid tissue with no duct, and are more 
abundant in the large intestine. 

Glands of Peyer are groups of the preceding, found for the most 
part in'the ileum ; they are one hundred in number ; the largest are 



128 EQUINE ANATOMY. 

\]/ z inch square, oval in shape, and situated opposite the mesenteric 
attachment. 

Blood Supply. — Caecal vessels. 

Nerves. — Sympathetic. 

Large Colon. 

About twelve feet long ; it begins at the caecum, passes forward, 
then bends backward and to the left, forming the supra-sternal curva- 
ture, lying above the sternum, then backward, turns again, forming 
pelvic flexure ; runs forward to the diaphragm, forming a flexure of 
the same name, then passes back with first portion, terminating in the 
small colon, after diminishing in calibre. 

Coats. 

Serous does not completely cover it. 

Muscular and mucous same as ccecum. 

Blood Supply. — Colic vessels. 

Nerves. — Sympathetic. 

Small Colon. 

About ten feet long, ending at the rectum. Has two longitudinal 
bands of fibres, and is lodged in the left flank. 

Coats. 

Same as preceding. 

Interior shows folds like large colon, which mould faeces. 

Vessels, small and great mesenteries. 

Rectum. 

About two feet long, from the pelvic inlet to its outlet, ending in the 
anus. 

It is very dilatable ; has no ridges, and is in relation to the sacrum 
above and the genito-urinary organs below. The suspensory liga- 
ments of the penis form a ring around its posterior portion. 

Coats. 

Serous is incomplete behind. 

The other coats are like those of colon. 

Vessels, small mesenteric and internal pudic. 

Anus. 

The posterior opening of the alimentary canal ; is situated under 



VISCERAL ANATOMY. 1 29 

the base of the tail. It receives an aggregation of the circular fibres, 
which form the internal sphincter. 

External Sphincter arises from the base of the tail, includes 
anus, and ends in perineal muscles. 

Action, by constant tension, keeping anus closed. 

Retractor Ani arises from the sacro-ischiatic ligament and is 
inserted into sides of rectum. 

Action, pulls rectum forward after defecation. 

Liver. 

The liver is situated in the abdomen, in the right diaphragmatic 
region. Its weight is eleven pounds. It has anterior and posterior 
flattened surfaces ; thick at its centre, thin on its edges. 

Lobes. 

Left (largest), right, Spigelian and middle. 

Fissures. 

(1) A deep one for the posterior cava ; (2) another in the centre of 
its posterior surface for the portal vein and vessels ; (3) one for the 
oesophagus ; (4) and one dividing the right and left lobes. 

Ligaments. 

(a) Anterior or coronary, from fissure for cava to phrenic centre. 

(b) Of left lobe, from left lobe to side of oesophageal orifice. - 

(c) Of right lobe, from lumbar wall to right lobe. 

(d) Broad or suspensory , from middle lobe to upper part of inferior 
abdominal wall. 

(e) Roitnd, from umbilicus to middle lobe. It is a fibrous cord 
formed by the obliterated umbilical vein. 

Structure. 

Serous coat externally, covering it completely, except at the anterior 
and posterior fissures and forming ligaments. 

Fibrous (Glisson's capsule), enters posterior fissure and follows ves- 
sels, after forming an outer envelope for the whole organ. 

Parenchyma or essential secreting portion, consists of. 

Lobules (yV to -^q inch in diameter), which comprise liver cells, 
polygonal in shape, -Jq to -^^ inch in diameter with one or two 
nuclei. They lie in a network of small vessels. 

Hepatic ducts begin between the liver cells, enter the peri-lobular 



i 3 o 



EQUINE ANATOMY, 




VISCERAL ANATOMY. I3I 

connective tissue, unite with others getting constantly larger, and 
finally, by several branches from the different lobes, form the 
ductus choledochus or great bile duct. This ascends in the gastro- 
hepatic amentum to the duodenum, which it penetrates six inches from 
the pylorus, surrounded by a circular fold of mucous membrane, the 
ampulla of Vater, in common with the pancreatic duct. The horse 
has no gall bladder. 

Course of blood through the liver. 

The portal vein enters the posterior fissure, forming inter-lobular 
veins ; these form a network of veins between the cells, then uniting, 
form the intra- lobular or central vein. 

The intra-lobular unite in the sub-lobular vessels, which are quite 
numerous, ending as hepatic veins by opening into the posterior 
cava. 

Lymphatics. 

Follow the vessels forming lymph spaces which, uniting, end in the 
1-eceptaculiim. 

Arteries. 

Hepatic, from cceliac axis, ending in the lobular centres. 

Nerves. — Solar plexus, tenth and phrenic. 

PANCREAS. 

This viscus resembles the salivary gland in structure, is situated in 
the sub-lumbar region, under the aorta and cava, and behind the 
stomach and liver. 

Form, elongated, triangular or curved on itself. 

Weigfit, seventeen ounces. 

It has a superior and inferior surface, an anterior and posterior 
border, a right extremity or head, and a left or tail, toward the spleen. 
The posterior border is notched for the portal vein. 

Structure. 

Like the salivary glands, though its epithelium is rounded, not 
columnar. 

Ducts. 

Principal (duct of Wirsung) runs along nearer anterior border, from 
tail to head receives a number of branches, and opens into duodenum 



I32 EQUINE ANATOMY. 

in common with the bile duct. The accessory duct opens alone after 
receiving several branches. 

Vessels. — Hepatic and great mesenteric. 

Nerves. — Solar plexus. 

SPLEEN. 

This is not properly an annexed gland of digestion, but from its 
position it is discussed in this section. It has no duct and is, therefore, 
a ductless glantl. 

It is situated in the diaphragmatic and left hypochondriac regions, 
and suspended from the sub-lumbar. Its shape is falciform, and 
directed downward and backward. 

Weight, thirty-two ounces. 

It has an external convex face, an internal concave, a convex 
posterior and concave and sharp anterior border, a base or superior 
extremity, and a point or inferior extremity. 

Ligaments. 

Suspensory ', from sub-lumbar region and left kidney to base. 
Gastro-splenic omentum, a process of peritoneum enveloping whole 
organ except at anterior fissure. 

Structure. 

Serous coat, from peritoneum, most external. 

Fibrous coat, thick and strong, sending prolongations or trabecular 
into the interior which support the splenic pulp. 

Splenic pulp, reddish material which fills the interior of the organ ; 
composed of pigment, broken down corpuscles, etc. 

Malpighian corpuscles, small rounded bodies of lymphoid structure 
enveloped by the outer tunic of the small arteries. They are large in 
well fed, and small in starved animals. 

Vessels. — Splenic. 

Nerves. — Solar plexus. 

THE PERITONEUM. 

The peritoneum is a serous membrane with a visceral and parietal 
layer, and enveloping nearly all the organs of the abdominal cavity 
more or less completely. 

Beginning at liver it forms the ligaments already described, a fold, 
the gas tro- hepatic omentum, which separates, to enclose the stomach, 



VISCERAL ANATOMY. 1 33 

and sending reflections to the duodenum and caecum on the right, 
and the spleen on the left forming the gastro-splenic omentum. Its 
median portion descends in front of the intestines, having a large 
amount of fat developed in its structure, the great omentum. This is 
confounded laterally with the mesenteries of the colon. 

The great omentum communicates with the general peritoneal 
cavity behind the stomach by an opening, the forame?i of Winslow, 
bounded by the vena porta', cava, pancreas and lesser curvature of 
the stomach. 

It is then reflected over the small and large intestines, forming their 
mesenteries, the ligaments of the bladder, broad ligaments of the 
uterus, and then from the rectum and front of the bladder is reflected 
to the superior and inferior abdominal wall, forming the parietal 
layers. The inferior abdominal portion continues forward and forms 
the suspensory ligament of the liver. The superior abdominal portion 
passes beneath the kidney, giving it support, and after forming the 
mesenteries is continued to the diaphragm, as the upper layer of the 
suspensory and gastro-hepatic ligaments. 

Structure. 

A basement membrane covered with flattened polygonal endothe- 
lial cells. 

RESPIRATORY SYSTEM. 

In this system, the great process of oxygenation of the blood takes 
place, as well as the throwing off of excrementitious substances, viz., 
carbonic acid gas, solids, etc. 

The air passages are from above, downward, the nasal fossa', larynx, 
trachea, bronchi and lungs. 

For a description of nasal fossa?, see special senses. 

LARYNX. 

The larynx is a cartilaginous box, being the organ of voice. Its 
anterior opening is at the bottom of the pharynx, its posterior con- 
tinuous with the trachea. 

Structure. 

Five cartilages, twelve muscles, and a mucous membrane. 
Cartilages. 

Thyroid, cricoid and epiglottis, single ones and one pair, the ary- 
tenoids. 



134 EQUINE ANATOMY. 

Thyroid. 

(Shield-like). Composed of two portions united in front and above 
to form its body ; to its superior part the epiglottis is attached. The 
lateral portions have an external surface, covered by muscles ; an 
internal, covered by mucous membrane ; an anterior or superior 
border, to which the great cornua of the hyoid and the thyro-hyoid 
membrane is attached ; a posterior border, showing in front the 
attachment of the crico-thyroid membrane, and behind an articulating 
facet with the cricoid. 

Cricoid. 

(Like a ring.) Shaped like a seal ring with the seal upward, and 
shows an external face, smooth, and on' its flattened portion spaces for 
the origin of the posterior eric o- arytenoids, outside these the articular 
facets for the thyroid ; an internal', face, covered by mucous mem- 
brane ; a superior border, with facets for the arytenoids and attach- 
ment of crico-thyroid membrane; an inferior border, responding to 
the trachea. 

Epiglottis, 

A soft, flexible lid that covers the entrance to the larynx. It has 
an anterior face, which gives- attachment to the hyo-epiglottideus ; a 
posterior, covered by mucous membrane ; a circumference and base 
attached to the thyroid. 

Arytenoids (two). 

(Like a pitcher.) Are situated above the cricoid and near the top 
of the larynx. They are irregularly quadrilateral and show an internal 
face lined with mucous membrane ; an external, giving attachment 
to arytenoid, thyro-arytenoid and lateral crico-arytcnoid muscles ; a 
superior border, united with the opposite ; an inferior, giving attach- 
ment to the vocal cord ; an anterior, joining with its fellow and 
giving the pitcher appearance ; a posterior, which articulates with 
cricoid. 

Articulations of Cartilages. 

Thyroid, with cornua of hyoid, by thyro-hyoid ligament and thyro- 
hyoid membrane. 

Thyroid with cricoids 

Capsular ligaments for facets and crico-thyroid membrane. 

Arytenoids with cricoid. 

By capsular ligaments for facets. 



VISCERAL ANATOMY. I 35 

Arytenoids with thyroid. 

By vocal cords, 3. pair of fibrous bands which enclose a triangular 
space, the glottis, attached in front to thyroid, behind to arytenoids. 

Epiglottis with thyroid, by simple ligamentous bands. 

Epiglottis with arytenoids, by some bands, sometimes called the 
superior or false vocal cords ; they contain some cartilaginous bodies 
(of Wrisberg). 

Fig. 22. 




POSTEROLATERAL VIEW OF THE LARYNX. 



i, Epiglottis; 2, Arytenoid cartilages; 3, Thyroid cartilage; 4, Arytenoideus muscle; 
5, Crico-arytenoideus lateralis ; 6, Thyro-arytehbideus ; 7, Crico-arytenoideus posticus ; 
8, Crico-thyroideus; 9, Ligament between the cricoid cartilage and first ring of trachea, 
10; 11, Infero-posterior extremities of crico-thyroid cartilages. 



Muscles. 
Thyro-hyoid. 

Origin. — Outer surface of thyroid cartilage. 
hisertion. — Whole hyoid cornua. 
Action. — Carries larynx forward and upward. 
Hyo-epiglottideits. 
Origin. — Body of hyoid. 
Insertion. — Superior face of epiglottis. 
Action. — Restores epiglottis to erect position. 



I36 EQUINE ANATOMY. 

Cri co- thyroid. 

Origin. — External face of cricoid. 
Insertion. — Posterior border of thyroid. 
Action. — Brings two cartilages together. 
Posterior crico- arytenoid. 
Origin. — Posterior flattened part of cricoid. 
Insertion. — Posterior tubercle of arytenoid. 

Action. — Rotates the arytenoids outward, thus separating vocal cords. 
Lateral crico-arytenoid. 
Origin. — Anterior border of side of cricoid. 
Insertion. — Outside the preceding on tubercle of arytenoid. 
Actioji. — Antagonist to preceding, approximating cords. 
Thyro-aryten oid. 

Origin. — By two fasciculi, near angle of thyroid. 
Ijisertion. — Lies on vocal cord, to external crest of arytenoid and 
muscles. 

Action. — Constrictor and regulator of tension of larynx. 

Arytenoid. 

Origin. — From external face of one cartilage. 
Insertion. — Into the analogous point of the other. 
Action. — Brings vocal cords in apposition. 

Mucous Membrane. 

Covered by flattened epithelium on cords and glottis ; elsewhere is 
ciliated. 

The glands are racemose and numerous posteriorly. 

Vessels. 
Laryngeal arteries. 

Nerves. 

Superior laryngeal supplies mucous membrane with sensation and 
crico-thyroid muscle. The inferior laryngeal supplies the remainder. 

In the mule and ass there exists a deep depression, the sub-epiglottic 
sinus, capable of great vibration. 

TRACHEA. 

This is a long tube composed of about fifty cartilaginous rings, 
beginning at the cricoid and ending at the right side of the posterior 
aorta opposite the left auricle of the heart. It lies under the cesopha- 



VISCERAL ANATOMY. 



*37 



Fig. 23. 




THE RESPIRATORY ORGANS; INFERIOR, OR FRONT VIEW. 

Trachea ; 2, Jugular vein ; 3, Great rectus anticus muscle ; 4, Carotid artery ; 5, Longus 
colli muscle ; 6, Origin of the common carotids ; 7, Vertebral artery ; 8, Section of first 
rib; 9, Cephalic trunk of right axillary artery; 10, Anterior lobe of right lung; 
11, Middle, or supplementary lobe of ditto; 12, Posterior portion or lobe of ditto ; 
13, Heart; 14, Cardiac artery; 15, Ventricular branch of cardiac vein; 16, OZsoph- 
agus. 



IO 



I38 EQUINE ANATOMY. 

gus and between the two carotids in the neck. At its end it bifurcates 
into the two bronchi. 

Structure. 

The cartilaginous rings are incomplete above, where the space is 
filled in by transverse muscular and fibrous bands. The rings are 
united by fibrous tissue which fill the intervening space. The last 
ring is often divided into two segments for the bronchi by a median 
spur. 

Mucous Membrane. 

Is covered by ciliated epithelium, and its glands are very numerous 
posteriorly. 

Vessels. 

From carotid and axillary. 

Nerves. 

From recurrent laryngeal. 

BRONCHI. 

The right and left primary bronchi are the continuation of the 
trachea, enter the root of each lung with the bronchial artery, veins 
and nerves. They then subdivide into a large number of branches 
which go on subdividing further. They are round, composed of car- 
tilaginous circles joined to each other by muscular fibre. The car- 
tilages and muscles disappear when the tubes become small. The 
mucous membrane is much more sensitive than that of the trachea, 
otherwise like it. 

Vessels, 
Bronchial. 

Nerves. 

From sympathetic and tenth. 

THE LUNGS 

Are the essential organs of respiration situated in the thorax on either 
side of the heart and enveloped by a serous membrane — the pleurae. 
They are described as two lungs, the right and left. Each lung is 
cone-shaped and has an external face lying against the ribs; an 
internal, forming the side of the mediastinum, which shows notches 
for the oesophagus and aorta ; the root of the lung, where the bronchi, 
vessels and nerves enter its structure, and the attachment of the 



VISCERAL ANATOMY. I 39 

ligamentum latum pulmonis, a process of the pleura passing backward 
to the diaphragm ; a base, concave and in contact with the diaphragm ; 
it shows a small lobule on the right side, which represents the middle 
lobe of man, and also a notch for the posterior cava. The apex or 
summit lies behind the first rib and is somewhat detached, forming 
the anterior lobe. Thus the right lung has three lobes, an anterior, 
middle and posterior, the left two, an anterior and posterior. The 
superior border lies near the vertebrae ; the i?iferior is notched deeply 
for the heart. 

Structure. 

Serous from pleura. (See below.) 

Parenchyma. — This is rose-colored, soft, strong and elastic. It is 
divided into lobules, each of which receives a small bronchus, and is 
further subdivided into alveoli, spaces with which a number of smaller 
spaces communicate, the air cells. The walls of the air cells have a 
thin basement membrane, covered with flattened epithelium 1 ^ 00 to 
22V0 °f an mcn m diameter. Between the air cells is yellow elastic 
connective tissue. 

Vessels. 

The vessels are derived from the pulmonary and bronchial arteries 
and the pulmonary vein. They form a plexus under the walls of the 
air cells, which allows the passage of oxygen. 

Nerves. 

Tenth and sympathetic. 

THE PLEUR.E. 

The pleurae are two shut serous sacs, which form the borders of the 
mediastinae, or space in centre of the chest. 

Structure. 

Basement membrane covered by flattened epithelium and lubricated 
by a serous fluid. 

Attach?nents. 

It is attached to the root of the lung, there giving off the ligamentum 
latum, then envelops the whole lung, forming the visceral layer. It 
then passes to the chest wall, forming its costal portion, to the dia- 
phragm, and at its middle is in contact with that of the opposite side, 
forming its mediastinal portion ; encloses the heart, and divides the 
chest into the anterior and posterior mediastince. 



I40 EQUINE ANATOMY. 

Nerves, 

Diaphragmatic, intercostal, tenth and sympathetic. 

Vessels. 
Bronchial and intercostal. 

THORAX. 

This cavity is bounded in front by the first ribs and longus colli, 
and has passing through this opening lymphatic glands, trachea, 
oesophagus, axillary and carotid vessels, anterior cava, tenth, sympa- 
thetic, inferior laryngeal and phre7iic nerves ; behind, by the dia- 
phragm ; above, the vertebra, ribs, longus colli, thoracic duct, aorta, 
vena azygos and sympathetic ; below, by sternum, costal cartilages and 
the triangularis sterni; laterally, by ribs and deep intercostal muscles. 

The contents are heart and great vessels, lungs, oesophagus, trachea, 
nerves, thoracic duct, etc. 

THE MEDIASTINjE. 

The portion of the thorax in front of the heart is called the anterior 
mediastinum, that behind, the posterior. The former contains the 
trachea, oesophagus, anterior aorta and divisions, anterior cava, tho- 
racic duct, tenth, cardiac, recurrent and phrenic nerves, and thymus 
gland in young animal. 

The latter contains the posterior aorta, vena azygos, thoracic duct, 
oesophagus, tenth and left phrenic nerves, and ligamentum latum. 

Ductless Glands. 
Spleen, see Abdomen; supra-renal bodies, see Kidney ; pituitary 
gland, see Brain. 

THYROID GLAND. 

The thyroid is a gland, lying in the neck under the first two tra- 
cheal rings, composed of two lateral lobes, a right and left, united by 
a median portion, the isthmus. 

Structure. 

Fibrous coat, which covers it, and sends in prolongations, as in the 
spleen. 

Parenchyma. — This is divided into lobules, which contain round 
vesicles, lined with polygonal cells, and containing albuminous matter. 
Vessels. 

Thyro-laryngeal. 

Nerves. 

First and second cervical and sympathetic. 



VISCERAL ANATOMY. 141 

THYMUS GLAND. 

.This is a gland lying at the back part of the neck, under the 
trachea, and partly within the thorax. It has two lateral lobes in 
contact with each other, and is only found in the foetus and young 
animal. 

Structure. 

Of lobules, which contain spaces filled with granular matter. 

The lymphatics are well marked. 

URINARY ORGANS. 
They comprise the kidneys, ureters, bladder and urethra (in the 
male this is also genital). 

THE KIDNEYS. 

The essential organs of the urinary system are two in number, 
situated in the abdomen, to the right and left of the sub-lumbar region, 
against the psoas muscles. The peritoneum passes under them. The 
right is heart-shaped and more anterior than the left, which is bean- 
shaped. 

Weight, — Right, twenty-seven ounces ; left, twenty-five. 

Each kidney has a superior and inferior flattened surface, an exter- 
nal convex border and an internal concave one, which is deeply 
notched, and called the hilum. The hilum lodges the vessels, nerves 
and beginning of the ureter. 

Interior. 

A section shows that at the hilum is found a cavity, called the 
pelvis, the beginning of the ureter, elongated from before backward. 
Opposite this, in the proper tissue of the kidney, is seen a ridge, on 
which empty the uriniferous tubes. The pelvis is lined with mucous 
membrane. 

Structure. 

Fibrous coat or capsule, most external, and sending prolongations 
into its interior. 

Parenchyma. — Divided into an external or cortical and internal or 
medullary layer. The cortical layer is darker, and contains small, 
round bodies, the Malpighian corpuscles. The medullary is lighter, 
and contains the uriniferous tubules. There is also some connective 
tissue supporting the tubes, vessels, etc. 



Fig. 24. 




VISCERAL ANATOMY. 143 

Malpig-hian Bodies. 

These are small, round vesicles found in the cortex, lined with 
cylindrical epithelium, and containing a tuft of blood vessels (the 
glomerulus), also covered by epithelium. There are two openings, — 
one, the beginning of the uriniferous tubule, the other opposite it, 
showing the entrance of a small artery and the emergence of a vein, 
which afterward forms a plexus around the tube. 

Uriniferous Tubes. 

These are small canals running through the medullary structure of 
the viscus, beginning at the Malpighian corpuscle, and ending on the 
ridge of the pelvis. They are first single, but soon subdivide into 
straight tubules, then descend into the medulla as the loop of Henle, 
in a U shape, turn on themselves and run back to the cortex. Then 
dilating, have several bends, pass down again through the medulla, 
narrow and empty on the ridge of the pelvis, as the convoluted tube. 

Structure. 

Amorphous basement membrane covered with flattened, polygonal 
or polyhedral epithelium in different localities. 

Vessels. 

The renal artery divides into several which give off branches to 
cortex and medulla, glomeruli and tubes. 

The branches to the medulla descend between the tubes. 

The veins of the capsule are collected in a stellate manner, the stars 
of Verheyen. They also form arches at the junction of the cortex and 
medulla, and finally uniting form the renal vein. 

The nerves are from the solar plexus. 



Fig. 24. — SUPERIOR AND GENERAL VIEW OF THE GENITO URINARY APPARATUS IN THE MALE, 

WITH THE ARTERIES. 

A, Left kidney ; b, Right kidney; a, b, Ureters ; c, c, Supra-renal capsules; d, Bladder ; 
e, e, Testicles; e, Head of the epididymus; e' , Tail of the epididymus; f, Deferent 
canal ; g, Pelvic dilatation of the deferent canal; h, Left vesicula seminales ; the right 
has been removed, along with the deferent canal of the same side, to show the insertion 
of the ureters into the bladder; 1, Prostate; j, Cowper's glands; k, Membranous, or 
intra-pelvic portion of the urethral canal; l, Its bulbous portion ; m, Cavernous body 
of the penis ; m, m, Its roots ; n, Head of the penis. 1, Abdominal aorta ; 2, 2, Arteries 
(renal) giving off the principal capsular artery; 3, Spermatic artery; 4, Common origin 
of the umbilical and arteries of the bulb ; 5, Umbilical artery; 6, Its vesical branch; 
7, Internal artery of the bulb ; 8, Its vesico-prostatic branch. 



144 EQUINE ANATOMY. 

SUPRA-RENAL CAPSULES. 

The supra-renal capsules are two small elongated bodies lying to the 
urwer and inner side of the pelvis of the kidney. 
Form. — Elongated and flattened, two inches long ; right larger. 

Structure. 

External fibrous coat, which projects inward, forming spaces. 

Parenchyma. 

(a) Cortical substance. Dark-brown in color, and consists of 
granular nucleated cells. 

(b) Medullary substance. Yellow and soft, of a delicate reticular 
structure filled with cells and nerve structures. 

Vessels. — Mesenteries and renal. 

Nerves. — In large numbers from solar plexus. 

THE URETERS. 

The ureters are two in number, beginning at the pelvis of the kid- 
ney, run back and downward to the superior and posterior portion of 
the bladder, where they penetrate its muscular coat for an inch before 
opening into its interior. It is the size of a goose quill. 

Structure. 

External, fibrous layer; middle, of external, circular and internal 
longitudinal muscular fibre, and an i?iternal, mucous, ridged in its 
long axis, and covered with stratified pavement epithelium. 

THE BLADDER. 

This is a muscular bag in which the urine is accumulated before 
being discharged from the body. It occupies the inferior part of the 
pelvic cavity, and has three openings, the orifices of the two ureters 
and beginning of the urethra. 

Weight, sixteen ounces. 

Parts. 

Near the urethral opening, the neck ; between the urethral opening 
and the openings of the two ureters a triangular space, the trigone. It 
rests by its inferior surface, or base on the pubo-ischial symphysis. 
Its anterior extremity or fundus is in relation to the large colon. 
Above, it is in relation with the uterus and vagina, in the female, the 
seminal vesicles, and rectum in the male. 



VISCERAL ANATOMY. 145 

Coats. 

Peritoneal ox serous (external), covers only its anterior half; passes 
back farther superiorly. Forms three ligaments, one anteriormwo 
lateral. 

Muscular, of unstriped tissue of longitudinal, oblique and circular 
fibres. The latter very marked at the neck, the sphincter. 

Mucous. — Pale, covered with stratified and flattened epithelium, 
and contains simple glands. 

Vessels. — Internal pudic and umbilical. 

Nerves. — Pelvic plexus and last two sacral. 

For urethra in male, see Penis ; in female, see External Genitals. 



MALE GENITAL ORGANS. 

THE TESTICLES. 

The testicles are two oval tubular glands lying on either side of the 
penis and enveloped in a double bag of the abdominal skin and 
fascia, the scrotum. 

Coverings. 

1. Scrotum, of skin, with many sebaceous glands. 

2. Dartos, two pouches of contractile tissue, in contact in the 
median line, the septum scroti. 

3. Cremaster, from the ilio-lumbar aponeurosis to the outer side of 
the next covering. 

4. Fibrous tunic (infundibuliform fascia), covers the whole testis, 
and is a process of the transversalis fascia. 

5. Tunica vaginalis is a short serous sac, enveloping each testicle, 
derived from the peritoneum. It forms a covering for the sper- 
matic cord, and below is divided into a visceral layer, covering 
the testicle and epididymis, and a parietal, lying inside the fibrous 
covering. 

Its cavity contains some fluid, serous in character. 

Parenchyma. — This consists of the testis proper and a number of 
seminal tubes, which together form a body lying on top of the testis — 
the epididymis. 

Fibrous membrane (or tunica albuginea) is a strong fibrous envelope, 
which sends in prolongations or trabecular to its interior, dividing it 



I46 EQUINE ANATOMY. 

into lobules. At its upper border and in front it is thickened, and 
called the corpus highmorianunt or mediastinum testis ; through this 
the seminal tubules pass from the interior. 

The tubules are divided into groups or lobules, about 200 or 300 in 
number, each lobule being found between prolongations of the fibrous 
tunic, and about one or two yards in length. 

The tubules are about ^ho °f an mcn m diameter ; have a basement 
membrane, covered by several layers of epithelium, which fill the 
tube, spermatozoids being found in the lumen. 

The lobuli testis consist simply of these tubes much convoluted ; 
passing through the mediastinum, they unite in about twenty tubes — 
the vasa recta ; forming a network, the rete testis, and are continued 
into the epididymis and the vasa efferentia. 

THE EPIDIDYMIS. 

The epididymis is an elongated body lying on top of the testicle, 
and composed of the seminal duct, much convoluted, the vasa effer- 
entia uniting to form it at its anterior portion — the head, or globus 
major. The posterior extremity, or tail, is called the globus minor. 
Between the globi is the body. The seminal duct, or vas deferens, is 
continuous with the globus minor. 

Structure. 

Externally a circular and longitudinal muscular layer, with a fibrous 
covering, covered by a mucous membrane lined with ciliated epithe- 
lium. 

Arteries. 

Spermatic, from the aorta. 

Veins are markedly spread out on the cord, the pampinifonn plexus, 
which finally empties into the posterior cava. 
Nerves. 
From sympathetic. 

Descent of the Testis. 

The testicle remains in the abdominal cavity, in the sub-lumbar 
region, till after birth, usually reaching the scrotum at the age of six 
months. The active part in the descent is taken by the gubernaculum 
testis, a fibrous cord continuous below with the dartos and ending 
above in the abdominal cavity. It pulls the testis downward, carrying 
the peritoneum before it, which becomes inverted over it, forming the 



VISCERAL ANATOMY. 1 47 

tunica vaginalis. The portion at the upper part of the scrotum be- 
comes obliterated and cut off from the peritoneal cavity. 

The semen, the combined secretion of the testicles and glands of 
the urethral canal, is a white, viscid, alkaline fluid, holding in solution 
the essential elements formed by the testicles — the spermatozoa — 
which are elongated bodies -^ to -^ inch long, with an oval head 
and a filamentous tail. 

VAS DEFERENS. 

This is an elongated canal, as large as a goose quill, beginning at 
the epididymis and ending at the seminal reservoirs. It passes up- 
ward through the inguinal canal, backward into the pelvis, crossing 
the ureters, and ends by uniting with the vesicles to form the ejacu- 
latory ducts. 

Structure. 

External, fibrous layer. 

Middle, muscular, of two longitudinal and one circular, layer. 

Internal, mucous, covered with columnar epithelium. 

THE VESICUL.E SEMINALES. 

These are two elongated pouches, which store up the semen for the 
copulative act; they lie above the bladder, receiving a peritoneal fold. 
They have a body and an anterior and posterior extremity. Their 
posterior extremity is tapering and unites with the vas to form the 
ejaculatory duct. 

Structure. 

1. Serous coat, incomplete. 

2. Fibrous. 

3. Muscular, like bladder, with also some compressor fibres to evacu- 
ate the pouch. 

4. Mucous membrane, continuous with ejaculatory ducts, thrown 
into folds with numerous glands, which furnish a part of the seminal 
fluid. 

THE EJACULATORY DUCTS 

Are two very short canals succeeding the vesicles, and formed by 
their junction with the vasa deferentia. They pass above the prostate, 
finally emptying into the urethra on either side of an elevation, the 
veru montanum. In front of this is the opening which runs backward 
into the sac lying between the vesicles and inside the peritoneal 



I48 EQUINE ANATOMY. 

pouch. The opening is the sinus pocularis, and the pouch the third 
seminal vesicle (this is not present in man to nearly the same extent). 

THE PROSTATE GLAND. 

The prostate is situated behind the neck of the bladder, and em- 
braces the beginning of the urethra, being divided into two lateral 
lobes. It contains a number of conglomerate glands, whose secretion 
is poured into the urethra on the sides of the veru montanum. It also 
contains fibrous structure. 

THE URETHRA. 

This is an elongated canal continuing through the whole penis, and 
beginning at the neck of the bladder as the meatus internus. 

It first passes backward, curves around the ischial symphysis, and 
then downward and forward in the structure of the penis, between 
the two corpora cavernosa. 

Divisions. 

Prostatic region, dilated, contains veru montanum, sinus pocularis, 
and openings of prostatic glands. 

Me?nbranous, from prostate to beginning of the spongy tissue {cor- 
pus spongiosum). 

Spongy or extra-pelvic. 

Begins near exit from pelvis, is narrowed and terminates on the 
g/ans, as the urethral tube. Just before this, it is dilated, the fossa 
navicularis. Behind the prostate are also the openings of Cowper s 
glands. 

Structtire. 

Mucous membrane, thin and covered by columnar epithelium ; in 
some parts flattened. 

Erectile tissue. 

Commences at ischial symphysis as the bulb, spreading out in front 
to form the glans penis, into which the cavernosa are inserted. 

Its structure consists of fibrous spaces with some elastic tissue, 
which cause erection mechanically, by their distention with blood. 
(For muscles see Perineum?) 

cowper's glands. 
These are two in number, of about the same structure as, and smaller 
than the prostate, situated near the outlet of the pelvis, on each side 
of the urethra, and throwing their secretion into it. 



VISCERAL ANATOMY. 1 49 

THE PENIS. 

The penis is the organ of copulation, attached behind to the ischium 
and extending forward between the thighs, under the abdomen, where 
it ends in a free extremity, the glans, the anterior termination of the 
spongy body. 

It consists of three portions, the two corpora cavernosa, between and 
below which is the urethra, enclosed in its spongy tissue. The free 
portion is lodged in the sheath or prepuce. 

Urethra, see above. 

Corpora Cavernosa. 

Are divided only posteriorly where they are attached to the ischial 
rami, but are blended in front, ending by entering depressions in the 
glans. Underneath is the groove which lodges the urethra. 

Structure. 

An external thick fibrous coat, giving off a median prolongation, 
the septum pectiniforme % which separates the two portions. 

The interior is composed of cavernous or erectile tissue like the 
spongiosum. At its base are found bouquet-shaped arterial tufts, 
called arterial helicina?. 

The free portion of the penis has an enlarged base, and an anterior 
extremity, the glans, which is rounded and limited behind by a 
marked elevation, the corona glandis. It receives behind the inser- 
tion of the corpus cavernosum. Below this the urethral tube, encircled 
by the urethral fossa ; under this a marked notch. The glans is cov- 
ered by a dark smooth skin, with many papillae. 

Suspensory ligaments of penis (2). 

Arise beneath sacrum, pass downward, encircling rectum, and 
inserted into the accelerator. 

Prepuce or sheath. 

A fold of the abdominal integument encircling the penis. It con- 
tains internally a number of sebaceous glands. It has in its structure 
two fibrous bands, the suspensory ligaments of the prepuce. 

Blood Supply. — Bulbo-uretjiral, dorsal arteries and of corpora 
cavernosa. 

Nerves. — Internal pudic and sympathetic. 



150 EQUINE ANATOMY. 

THE PERINEUM. 

The. perineum is the space lying below the rectum, and on the sides 
of the external genitals in both sexes. 

Superficial Fascia. 

Arises from inner sides of thighs. Inserted on muscles of peri- 
neum and sphincter ani. 

Deep Fascia. 

Arises from ischial tuberosities, rectal muscles and thighs. 

Inserted, between ischio-cavernosus and semi-membranosus \ into 
perineal muscles and fascia. 

Muscles. 

(a) Wilson's muscle. 

Origin. — From sides of pelvis. 

Insertion. — By superior and inferior fasciculi into urethra in its 
membranous portion. 

(b) Accelerator urines. 

Origin. — From under surface of urethra. 

Inserted. — Into top of urethra often passing around it ; extending 
from ischium to end of penis by transverse fibres. 

(c) Ischio-urethral (compressor urethrae). 
Origin. — From ischial arch. 

Insertion. — Into lower face of Cowper's gland and Wilson's muscle. 

(d) Transversus perinei. 
Origin. — Ischial spine. 

Insertion. — Into median perineal line. 

Action of Muscles. 

The first and third compress the urethra. 

The second acts more especially in emptying it of urine, or semen. 

The fourth dilates the urethra. 



FEMALE GENITALS. 

THE VULVA. 

The external orifice of the female genitals is situated below the anus 
in the perineum. It is a slit-like opening, extending vertically, termi- 
nated above and below in the superior and inferior commissures. The 
sides are formed by the labia (or lips), of skin externally, and mucous 



VISCERAL ANATOMY. 151 

membrane internally. The different structures composing it are the 
clitoris, urethra and hymen. 

The Clitoris. 

This is a body two or three inches long ; lies at the inferior com- 
missure ; is composed of erectile tissue, two crura, a prepuce and glans. 

The Female Urethra 

Is very short, and opens by its meatus about three or four inches 
from the vulva on its inferior wall. It is guarded by a mucous 
valve which directs the urine backward. Its calibre is greater than 
in the male. Its coats are an internal mucous and external muscular, 
of circular fibres. 

The Hymen. 

Rare. A thin, fibrous structure, shutting off the vaginal from the 
vulvar cavities. It is perforated by several openings. 

Structure of Vulva. 

Mucous membrane \ with many mucous and sebaceous glands. 

Bulb of Vulva. — Consists of two lateral lobes of erectile tissue, 
communicating with the vessels of the clitoris, lying on either side of 
the vulva. 

Muscles. 

Constrictor vuIvce. 

Attachments. — Above to sacrum and sphincter, and below to clitoris ; 
laterally to muscles of thigh. 

Action. — Constricts vulvar orifice. 

Constrictor vagince. 

Attachments. — To sides of rectum and vagina at junction with vulva. 

Action. — Constricts vagina. 

THE VAGINA. 

The vagina is a long, membranous tube, extending from the vulva 
to the uterus, and serves the purposes of coition and passage of the 
foetus. 

Relations. 

Above, rectum; below, bladder; laterally, ureters and connective- 
tissue. 

Structure. 

Inner or Mucous Coat. — Pale ; a basement membrane, covered with 



152 EQUINE ANATOMY. 

a flattened epithelium. Is covered with an abundance of mucus, and 
has longitudinal folds (ruga). 

Outer or Muscular. — Of circular and longitudinal unstriped fibres. 

Serous or Peritoneal. — Only in its anterior part. 

Vessels. 
Internal pudic. 

Nerves. 
Pelvic plexus. 

THE UTERUS. 

The uterus is a hollow, muscular organ, in which the ovum is 
received, and the foetus developed. It is situated in the abdominal 
cavity in the sub-lumbar region, its posterior extremity ending in the 
pelvic cavity. 

Relations. 

Above, to rectum ; below, with bladder ; anteriorly and laterally with 
intestinal convolutions : behind, with vagina. 

Parts. 

Behind is a constriction, the cervix (or neck), with a circular open- 
ing, the os. In front is the fundus, directly continuous with the two 
cornua. These have a superior or convex, and posterior or concave 
curvature, a base continuous with the uterus, and a summit continuous 
with the oviducts. 

Ligaments. 

Two broad, descending from the sub-lumbar region to the sides of 
the uterus and cornua and enveloping the ovaries and their ducts. 

Two rudimentary, round ligaments, running from the sides of the 
uterus to the beginning of the inguinal canal. 

Structure. 

Serous coat, complete, from peritoneum. 

Muscular coat, longitudinal (external) and circular (deep) unstriped 
fibres. The latter most marked about the cervix. 

Some muscular fibres pass into the broad ligaments. 

Mucous coat, of basement membrane covered with ciliated epithe- 
lium, except at the cervical canal, where it is columnar, and at the os, 
where it is flattened. It is thrown into folds at the cervix and is 
divided into two canals — those of the cervix and body. It is supplied 
with mucus by numerous simple and cylindrical glands. 



VISCERAL ANATOMY. I 53 

Blood Supply. 

Uterine and utero-ovarian vessels. 

Nerves. 

Mesenteric and pelvic plexuses. 

THE OVIDUCTS, OR FALLOPIAN TUBES. 

The oviducts are two tubes, lying on either side of the uterus, in the 
broad ligaments, which serve for the passage of the ovum from the 
ovary to the uterine cavity, with which they are continuous, and open 
into the cornua, by a narrowed orifice on a tubercle. In its middle 
it is narrow, and at its ovarian extremity it is dilated and divided into 
several narrow prolongations, the fimbriated extremity, one of these 
communicating with the ovary. 

Structure. 

Serous coat, from broad ligament. 
Muscular, of circular and longitudinal fibres. 

Mucous, continuous with that of the uterus, covered by ciliated 
epithelium and thrown into longitudinal folds. 



THE OVARIES. 

The ovaries are two small ovoid bodies, situated in the sub-lumbar 
region, with a deep notch or hilus on their upper surface which re- 
ceives the oviduct. Into this the ovum is discharged. It is attached 
by the ovarian ligament to the uterus, and supported by the broad 
ligament. 

Structure. 

Serous coat, complete except at hilus. 

Fibrous coat (or timica albugined), very strong. 

Stroma, hard and grayish-red. Is divided into an external cortical 
and internal medullary portion. 

Medulla, red and spongy, of connective tissue and vessels. 

Cortex, of connective tissue, holding large numbers of Graafian 
vesicles or ovisacs which contain the ova. In the fully formed state 
they project on the surface and are composed of a tunica fibrosa, 
tunica granulosa and discus proligerus, a collection of cells about 
the ovum. 
ii 



154 



EQUINE ANATOMY. 
Fig. 25. 




VISCERAL ANATOMY. I 55 

Blood Supply. 
Utero-ovarian. 

Nerve. 
Mesenteric plexus. 

THE MAMMARY GLANDS. 

The mammas are two glandular bodies situated in the posterior and 
inferior abdominal region, in the position of the scrotum in the male. 
They are hemispherical in shape, terminating below in a small promi- 
nence, the nipple or teat. 

Structure. 

Skin, of abdominal region, thin and soft. 

Fibrous coat, of elastic fibrous tissue, which sends prolongations into 
its interior. 

Parenchyma -of vesicles or acini, opening into lactiferous ducts. 
These unite and form several canals. These form two, three or four 
sinuses opening by several canals on the nipple. The acini are lined 
with polyhedral epithelium which become rounded and fatty in 
lactation. 

Blood Supply. 
External pudic. 

Nerves, 

First lumbar. 



ORGANS OF SPECIAL SENSE. 
Smell. — Located in the nasal cavities. 

THE NASAL CAVITIES. 

Bony waits. 

Floor. 

Two superior maxillary, two inter- maxillary and two palate bones. 

Fig. 25. — GENERATIVE ORGANS OF THE MARE, ISOLATED AND PARTLY OPENED. 

i, i, Ovaries ; 2, 2, Fallopian tubes ; 3, Pavilion of the tube, external face; 4, Ibid., inner 
face, showing the opening in the middle ; 5, Ligament of the ovary ; 6, Intact horn of 
the uterus ; 7, A horn thrown open; 8, Body of the uterus, upper face ; 9, Broad liga- 
ment; 10, Cervix, with its mucous folds ; 11, Cul-de-sac of the vagina; 12, Interior of 
the vagina, with its folds of mucous membrane ; 13, Urinary meatus, and its valve, 14 ; 
15, Mucous fold, a vestige of the hymen; 16, Interior of the vulva; 17, Clitoris; 
18, 18, Labia of the vulva ; 19, Inferior commissure of the vulva. 



156 EQUINE ANATOMY. 

Roof. 

Nasal, frontal, e thmoid and sphenoid. 

Sides. 

Nasal, inter-maxillary, superior maxillary, palate and turbinated. 

Median Septum. 

Perpendicular plate of ethmoid, vomer and mesial cartilage. 

Opening's of Communication. 

Anteriorly, two nostrils. 

Posteriorly , two posterior nares, with pharynx. 

Laterally, by a common opening into the middle meatus, the superior 
maxillary, sphenoidal, ethmoidal and frontal sinuses. The inferior 
maxillary opens alone. 

Above, the openings of the cribriform plate transmitting the olfactory 
nerves. 

Below, the incisive canal, leading to the mouth. 

THE NOSTRILS, 

Are two oblong openings in the anterior and inferior portion of the 
nose. 

Structure. 

Of three cartilages, the first one prolonged from the tip of the nasal 
bones, two lateral cartilages meeting in the median line in an x shape 
and attached at the side to the inter-maxillary bones by a broad ex- 
panded portion ; the lower extremity forms the curve of the nostril. 

Muscles. 

Already described. 

Skin. 

Thin and sensitive. 

Mucous Membrane. 

Covers the whole surface of the nasal cavities and continued into 
the sinuses. 

Divided into two portions. The olfactory in the upper one-third, 
which is thin, with columnar and stratified epithelium, and the cells of 
Schultze. These are fusiform in shape, with a deep prolongation, 
continuous with the olfactory nerve, and a superficial near the free 
surface of the membrane. It is supplied by the first nerve. 

The Schneiderian is thick, soft and spongy, with numerous vessels 



VISCERAL ANATOMY. I 57 

and glands. The epithelium is ciliated 'and supplied by the fifth nerve 
and its superior maxillary branch. 

Meatuses (three). 

Superior, above superior turbinated. 
Middle, between two turbinated. 
Inferior, below inferior turbinated. 

Blood Supply. 

Superior coronary, external nasal, palato-labial and ophthalmic 
arteries. 

Taste. 

The mucous membrane of the tongue is the seat of this sense. The 
tongue and the mucous membrane have been already described. 
(See Mouthy 

Nerve Supply. 

Posterior third 'by ninth nerve (glossopharyngeal). 

Anterior two-thirds by chorda tympa?ii (from seventh). 

The nerves end in the taste (or gustative) bulbs, which are found 
about the calyciform and fungiform papillae. They are fusiform in 
shape, their upper extremity reaching the mucous membrane. The 
nerve is found in the centre, and on the sides are protective cells, 
fusiform in shape, each with a special nucleus. 

Auditory Apparatus. 

Divided into three parts, the external, middle and internal ears, 
which collect, transmit and take cognizance of, sound. The internal 
ear, the essential part of the apparatus, being enclosed in the petrous 
portion of the temporal bone. 

EXTERNAL EAR. 

This consists of the external auditory canal and the concha or 
widened appendage. 

The Concha. 

This is pyramidal in shape, its apex directed forward and upward, 
convex externally, concave internally. It consists of three carti- 
lages, ten muscles, a fatty cushion and integument. 

Cartilages. 

(i) Conchal. — Of the general shape of the whole concha, and 
attached by the (2) Annular cartilage to the beginning of the external 
auditory meatus. 



158 EQUINE ANATOMY. 

(3) Scutiform. — A small plate lying in front of the base of the 
concha and attached to it. 

Muscles. 

There are a few intrinsic muscular fibres of little importance. 
Extrinsic are — 

1. Zygomatico-auricularis. 

Origin. — Zygomatic process of temporal. 
Insertion. — Outer side of base of concha. 
Action. — Carries ear forward. 

2. Tonporo-auricularis externus. 
Origin. — Parietal ridge. 

Insertio7i. — Conchal and scutiform cartilages. 
Action. — Draws ear forward and inward. 

3. Scuto-auricularis externus. 
Origin. — Scutiform cartilage. 
Insertion. — Inner side of concha. 
Action. — Rotates concha. 

4. Cervico-auricularis superior. 

Origin. — From external temporo-auricular. 
Insertion. — Posterior face of concha. 
Action. — Draws it back. 

5. Cervico-auricularis medius. 
Origin. — Preceding and following. 
Insertion. — Base of concha. 

Action. — Rotates concha out and back. 

6. Deep cervico-auricularis. 

Origin. — Under and upper extremity of parotid. 
Insertion. — Base of concha. 
Action. — Like preceding. 

7. Parotido-auricularis. 

Origin. — Outer surface of parotid. 
Insertion. — Base of and outside of concha. 
Action. — Abducts ear. 

8. Temporo- auricular is internus. 

Origin. — Under superficial of same name, from intra-parietal ridge. 
Insertion. — Inner side of concha. 
Action. — Adductor. 



VISCERAL ANATOMY. I 59 

9. Scuto-auricularis internus. 
Origin. — Beneath scutiform. 
Insertion. — Base of concha. 

Action. — Antagonizes No. 3. Turns ear outward and backward. 

10. Mastoido-auricularis. 

Origin. — Margin of auditory meatus. 

Insertion. — Into base of concha. 

Action. — Constricts meatus. 

Skin. — Thin, vascular, and covered with fine hairs. 

EXTERNAL AUDITORY CANAL. 

This is a short canal lodged in the petrous portion of the temporal 
bone, commencing at the external meatus and ending at the middle 
ear, being shut off from that cavity by the membrana tympani. The 
canal is lined with thin skin which contains a number of ceruminous 
glands which secrete cerumen or wax. 

MIDDLE EAR OR TYMPANUM. 

The tympanum is a cavity situated in the interior of the temporal 
bone at the junction of its mastoid and petrous portions, communi- 
cating with the pharynx by a canal lined with mucous membrane, the 
Eustachian tube. It has an external wall formed by the ?ne?nbrana 
tympani, an internal, shutting it off from the internal ear, showing two 
openings, the fenestra ovalis and fenestra rotunda, separated by an 
elevation, the promontory \ and a circtimference, which shows the 
openings of many mastoid cells. It is lined with mucous membrane 
continuous with that of the pharynx, and covered with pavement 
epithelium. 

The Membrana Tympani shuts off the external meatus from the 
tympanum, is concave externally, convex internally, set strongly in 
a bony depression and adherent internally to the handle of the 
malleus. It consists of three layers, a middle, fibrous and muscular, 
an external of skin, and an internal of mucous membrane. 

The Fenestra Ovalis, lying in front of the promontory, is oval in 
^hape, closed by the base of the stapes, and communicates with the 
vestibule. 

The Fenestra Rotunda communicates with the scala tympani 
and is closed in by a membrane. 



l6o EQUINE ANATOMY. 

The Mastoid Cells are small cavities communicating with the 
tympanum and lined by a reduplication of its mucous membrane. 

The Ossicles of the tympanum are four in number, the malleus, 
incus, os orbiculare and stapes. 

The malleus (hammer) shows a head for articulation for the incus, 
a handle for articulation with the membrane, and a neck showing two 
processes of insertion {processes gracilis and brevis). 

The incus (anvil) shows a body and two processes, the superior end- 
ing in a blunt point, the inferior being attached to the orbicular bone. 

The os orbiculare, a small, disk-shaped bone, lies between the incus 
and stapes. 

The stapes (stirrup) is shaped like a stirrup and has a head articu- 
lating with the preceding, two branches, united at a base, which fills in 
the fenestra ovalis. They are held together by unimportant ligaments. 

Muscles. — (Two of importance only.) 

Tensor tympani. 

Origin. — From Eustachian tube. 

Insertion. — Into neck of malleus. 

Action. — Carries handle of malleus inward, thus making membrana 
tympani tense. 

Stapedius. 

Origin. — Wall of tympanum, near f. vestibuli. 

Insertion. — Head of stapes. 

Action. — Tensor of membrana. 

The Eustachian lube is a canal of cartilaginous material running 
from the tympanum downward for a distance of four inches, to near 
the guttural openings of nasal cavity, where it is expanded into the 
guttural pouches. It is covered by the stylo-pharyngeus. 

Function. — Maintains the equilibrium of air inside the membrana 
tympani. 

The guttural pouches are two elongated cavities communicating with 
the pharynx, and lying on its sides. 

They are in relation externally to the carotid and parotid glands, 
and have a capacity of three-fourths of a pint, though capable of much 
greater distention. 

The mucous membrane is thick, strong and well lubricated with' 
mucus. 

Function. — Probably connected with hearing in some way, and also 
with phonation. 



VISCERAL ANATOMY. l6l 

THE INTERNAL EAR. 

The structures of the internal ear are contained in the petrous por- 
tion of the temporal bone forming the bony labyrinth, the parts them- 
selves being called the membranous labyrinth. 

The Bony Labyrinth consists of the vestibule, semicircular canals 
and cochlea. 

The vestibule lies inside the inner wall of the tympanum, receiving 
the fenestra ovalis, the five openings of the semicircular canals above, 
the commencement of the scala cochlece and the openings for the 
vestibular branches of the eighth nerve. 

The semicircular canals are three in number, opening at five points. 
They are named the superior, posterior, and external. 

The Cochlea (or snail shell) is situated outside and below the ves- 
tibule, consisting of a central stem, the modiolus, with a twisted parti- 
tion, the lamina spiralis, running about it, and dividing the cochlea 
into two portions, that above the partition, the scala tympani, com- 
municating with the tympanum by the fenestrum rotundum ; that 
below, the scala vestibuli, entering the vestibule. The lamina does 
not quite reach the outer wall of the cochlea. 

The Membranous Labyrinth consists also of the vestibule, semi- 
circular canals and cochlea. 

The vestibule consists of two thin sacs, a superior or utricle, commu- 
nicating with the semicircular canals, and inferior ox saccule, in contact 
with the former. 

The structure of the vestibule is an external fibrous coat and internal 
epithelial lining, with some calcareous particles (the otoliths) at the 
entrance of the nerves. 

The Membranous Semicircular Canals fill the bony canals, 
and are of the same structure as the vestibule. 
One of their extremities is dilated, the ampulla. 

The Membranous Cochlea. 

The lamina spiralis is continued by two membranes to the peri- 
phery of the cochlea, dividing it into the two already described — the 
s. tympani below and s. vestibuli above — and a median one between 
the two, the auditive, which contains the organ of Corti, a large num- 
ber of small epithelial elements, resting on the ?ne?nbrana basilaris, 
and having above the membrane of Corti. 



1 62 EQUINE ANATOMY. 

The organ of Corti is very intimately connected with the perception 
of sound. The scala vestibuli is again divided by the membrane of 
Reissner into two more canals. 

The Fluids of the internal ear are the endolymph, limpid and 
watery, inside the membranous labyrinth, and the perilymph outside 
the membranous portion. 

The Nerve Supply is from the eighth or auditory nerve, which 
splits up into vestibular branches, to the utricle, saccule and ampullce 
and cochlear branches to the different scalae of the cochlea. 



SIGHT. 

The eyes are two globular bodies, situated in the orbital cavities, 
that collect impressions of light, these impressions being carried to 
the brain by the optic or second pair of nerves. 

THE ORBITS. 

Two bony cavities, situated at the upper and anterior part of the 
face, containing the organs of vision. The bones entering into their 
formation are at its base the zygoma, the zygo?natic process of the 
temporal, molar, frontal and lachrymal. 

On the inner side are found the sphenoid, palate and superior max- 
ilia. The orbit is continuous behind, with the temporal fossa. On its 
inner side, anteriorly, is seen the lachrymal fossa. 

The foramina opening into it are the palatine, spheno-palatine, 
superior dental, optic, pathetic, lacerated and rotundum. 

THE EYE. 

The organs of vision consist of the two eyeballs and appendages. 

The eyeball is spheroidal in shape, a little longer in its antero-pos- 
terior diameter, where it is continued by the cornea. It lies in the 
fat of the orbit, held in position by its muscles, and consists of three 
tunics surrounding the humors. 

TUNICS. 

The tunics of the eye are the (i) sclerotic and cornea, (2) choroid 
and iris and (3) retina. 
The Sclerotic is the white, dense, outer coat into which the mus- 



VISCERAL ANATOMY. 1 63 

cles are inserted. The choroid lies in contact with it internally. It is 
continued in front as the cornea, and is pierced behind for the optic 
and ciliary nerves and central artery. 

The Cornea is the anterior one-sixth of the sclera. It is shaped 
like a watch-glass, convex in front, and transparent. It is composed 
of a middle proper structure of connective tissue, an anterior layer 
from the conjunctiva, and a posterior, elastic in structure, the mem- 
brane of Desce??iet. 

The Choroid lies between the sclera and retina, and is a thin, 
brownish, vascular membrane. 

Its coats from without inward (Strangeways) are — 

1. Me mbr ana fit sea, of connective tissue, vessels and nerves._ 

2. Vascular layer, containing many veins, the venae vorticosae. 

3. Tunica Ruyschiana, of capillary vessels from ciliary arteries. 
(The pigment layer of the retina was formerly included as a layer 

of the choroid). 

The Ciliary Muscle is a band of circular unstriped fibres running 
from the junction of the cornea and sclera to the iris. Its function is 
connected with accommodation. 

The Ciliary Processes are folds of the choroid anteriorly, about 
sixty to eighty in number and ^ inch in length. 

The Iris is a circular curtain, a continuation of the choroid anteriorly, 
yellowish-brown in color, with a central opening, the pupil. 

Structure. , 

(1) Anterior epithelial layer, continuous with the posterior corneal 
layer ; (2) middle musctdar, of circular and radiated unstriped muscular 
fibres, supplied by the ciliary ganglion ; (3) posterior epithelial 'or uvea, 
with numerous pigment cells. 

The Retina, or internal tunic, is the expansion of the optic nerve 
ending in a number of folds anteriorly, the zone of Zinn. Its layers 
from without inward are — 

1. Pigmentary, of hexagonal, pigment cells, formerly ascribed to 
choroid. 

2. Layer of rods and cones. 

3. External granular layer. 



164 



EQUINE ANATOMY. 



4. Intermediate layer. 

5. Inner granular layer. 



Fig. 26. 




THEORETICAL SECTION OF THE HORSE S EYE. 

a, Optic*nerve ; b, Sclerotic ; c, Choroid ; d, Retina ; e, Cornea ; f t Iris ; g t h, Ciliary circle 
(or ligament) and processes given off by the choroid, though represented as isolated from 
it, in order to indicate their limits more clearly; i, Insertion of the ciliary processes on 
the crystalline lens ; j, Crystalline lens ; k, Crystalline capsule ; /, Vitreous body ; 
m y n % Anterior and posterior chambers ; <?, Theoretical indication of the membrane of 
the aqueous humor; p,p y Tarsi ; q, q, Fibrous membrane of the eyelids ; r, Elevator 
muscle of the upper eyelid ; s, s, Orbicularis muscle of the eyelids ; t, t, Skin of the 
eyelids ; u, Conjunctiva ; v, Epidermic layer of this membrane covering the cornea ; 
x, Posterior rectus muscle ; y, Superior rectus muscle ; z, Inferior rectus muscle ; 
w, Fibrous sheath of the orbit (or orbital membrane). 



6. Molecular layer. 

7. Ganglionic layer. 

8. Optic nerve fibres. 



VISCERAL ANATOMY. 1 65 

At the point of entrance of the optic nerve, there is an oval point i 
inch in diameter, where all nerve elements are absent ; this is the 
blind spot. 

Humors. 
These are the aqueous and vitreous humors, and crystalline lens. 

The Aqueous humor fills up the space lying between the cornea, 
pupil and iris (anterior chamber), is alkaline in reaction, consisting of 
water with J^ solids. 

The Vitreous fills up the space inside the retina and lens. It con- 
sists of gelatinous tissue. 

The crystalline lens is y% by y% inches, lies behind the pupil and in 
front of the vitreous. It is a double convex lens of concentric layers 
with an external capsule. 

MUSCLES OF THE EYELID. 

Orbicularis palpebrarum. 
Origin. — Lachrymal tubercle. 
Insertion. — Skin of both eyelids. 
Action. — Sphincter of lids. 

Levator palp ebrce superioris extemus. 

Origin. — External surface of frontal near supra-orbital foramen. 

Insertion. — Into orbicularis. 

Action. — Wrinkles skin of upper lid. 

Levator palp ebrce superioris internus. 

Origin. — Superior border of optic foramen. 

Insertion. — Inner surface of upper lid and tarsal cartilage. 

Action. — Raises upper lid. 

Nerve Supply. 

The latter by motor oculi, the others by facial. 

MUSCLES OF GLOBE. 

Retractor oculi. 

Origin. — Optic foramen. 

Insertion. — Outer and back part of sclera. 

Superior, inferior, external and internal recti. 

Origin. — Margin of optic foramen. 

Insertion. — Above, below, outside and inside sclera. 



1 66 EQUINE ANATOMY. 

Superior oblique. 

Origin. — Optic foramen, passes to internal wall of orbit through a 
cartilaginous loop. 

Insertion. — Into sclera, between superior and external recti. 

Inferior oblique. 

Origin. — Lachrymal fossa. 

Insertion. — Under sclera. 

Action. — The superior rectus turns the globe upward, the inferior 
down, the external out, the internal in, the superior oblique upward 
and outward, the inferior oblique downward and inward, and the 
retractor oculi, as its name implies. 

Nerves. — The sixth nerve supplies the external rectus and retractor 
oculi, the fourth the superior oblique, and the third the remainder. 

APPENDAGES OF THE EYE. 

The Eyebrows are small and furnished with long hairs. 

The Eyelids are two in number, superior and inferior. The angles 
of continuatio?i are called the external and internal canthi. They are 
covered with skin externally and conjunctiva internally, with long 
hairs and orifices of Meibomian glands on the edges. Their frame- 
work is made up of muscles and tarsal cartilages, two thin plates, the 
upper being the larger. 

The Meibomian Glands pour out a sebaceous matter to lubricate 
the lids. They lie between the cartilage and conjunctiva and are 
tubular in character. 

The Conjunctiva is a mucous membrane, thin and vascular, 
lining the lids and covering the anterior part of the globe. 

The Membrana Nictitans is an accessory lid lying at the nasal 
angle of the orbit, composed of elastic cartilage. It serves to remove 
foreign bodies from the eye. 

The Caruncle is a small, red elevation at the inner canthus, which 
directs the tears toward the puncta. 

The Tear Apparatus consists of the lac hry??ial gland, canaliculi, 
lachrymal sac and nasal duct. 

The lachrymal gland is conglomerate, lying under the roof of the 



VISCERAL ANATOMY. 1 67 

orbit, and secretes the tears, which empty on the inner surface of the 
upper lid. 

The excess of tears enter the canaliculi, two small canals in the 
upper and inner lids, which run from openings on the lids, the puncta 
to the lachrymal sac, a dilatation in the lachrymal fossa. This sac 
forms the beginning of the nasal duct, which runs down in the lachry- 
mal bone as a membranous canal, to end near the nostril on its 
inner side. 

The Ocular Sheath is a firm, fibrous membrane binding the 
structures of the orbit together. 

Blood Supply. 

Ophthalmic, from i?iternal maxillary, giving off ciliary, arteria 
centralis retince, supra-orbital, and lachrymal to the gland. 



THE SEXSE OF TOUCH. 
The special sense of touch is located in the skin, being more 
marked in the lips and extremities. 

THE SKIN. 

The skin is the outer, enveloping membrane of the body, and con- 
tinuous with the outer limits of the internal mucous membranes. It 
is divided into the derma or cutis vera, internally, and the epidermis, 
externally. 

The Derma forms the greater part of the thickness of the skin, 
being continuous with the subcutaneous connective tissue, internally, 
and the epidermis, externally, where it contains little elevations, the 
papillcB. It is composed internally of loose meshed tissue, the corium, 
and externally of the papilla?, arranged in parallel rows about yi^ of 
an inch in length. 

The Epidermis, or cuticle, lying upon the derma, is more or less 
pigmented, and consists of an internal deep layer or rete mucosum, 
containing soft pigment cells and a superficial or horny layer of con- 
densed, horny, flattened cells. 

The Appendages of the Skin are the hairs, sudoriferous and 
sebaceous glands and horny parts. 



1 68 equine anatomy. 

The Hairs. 

The hairs are modifications of skin, and are divided into the hair 
proper, forming the coat, and horse hair, long and flowing, found in 
the forelock, mane, tail, eyelashes, lips and fetlock. 

Structure. 

Hairs consist of a free, projecting portion, the shaft, of three layers, 
an external of flattened epidermal scales, a middle or cortical of nar- 
row, epithelial lamellae, pigment and air globules, and an internal or 
inedullary of rectangular cells with fat and air globules ; a root lying 
imbedded in the skin, in an involution, the hair follicle with external 
and internal sheaths and resting on the papilla, from which it takes 
its nutrition and growth. 

The Sudoriferous Glands are attached to the skin, consisting of 
a curled tubule lying in the corium and a spiral duct passing up 
through the derma and epidermis, lined with epithelium. Their 
function is the regulation of animal heat, and also are connected 
with excretion. 

The Sebaceous Glands empty into the hair follicles or on the skin 
independently. They consist of vesicles filled with fatty and epithelial 
tissue, opening into a common duct. Their function is lubrication 
and protection as well as preservation of the elasticity of the hair. 

The Horny Parts. 

These comprise the chestnuts, ergot and hoofs. 

The Chestnut is a small growth of epithelial tissue, oval in form, 
at the inner side of the upper metatarsal region, where it is smaller, 
and at the inner side of the forearm. 

The Ergot is a similar structure attached to the skin of the fetlock. 

The Hoof. — The hoof is the complicated apparatus surrounding 
the third or distal phalanx, navicular bone, and part of the second 
phalanx. The bones, articulations, muscles, nerves and vessels may 
all be found under their headings. It also consists of the comple- 
mentary apparatus, keratogenous membrane and hoof proper. 

THE COMPLEMENTARY APPARATUS. 

This consists of the fibro- cartilages, two in number, united behind 
and below by the. plantar cushion. 

The Cartilages are two in number, attached in front to the 



VISCERAL ANATOMY. 



169 



anterior lateral ligament, behind to the basilar and retrossal processes 
and plantar cushion ; they are thin above, with a notch behind for 
vessels, thick below, concave internally, with vascular foramina, and 
convex externally, also with foramina for vessels. 

They are composed of fibrous and cartilaginous tissue. 



Fig. 27. 




LONGITUDINAL MEDIAN SECTION OF THE FOOT. 

i, Anterior extensor of the phalanges, or extensor pedis; 2, Lateral extensor, or extensor 
suffraginis; 3, Capsule of metacarpo-phalangeal articulation; 4, Large metacarpal 
bone ; 5, Superficial flexor of the phalanges, or perforatus ; 6, Deep flexor, or perforans ; 
7, Sheath ; 8, Bursa ; 9, Sesamoid bone ; 10, Ergot and fatty cushion of fetlock ; 
11, Crucial ligament; 12, Short sesamoid ligament; 13, First phalanx; 14, Bursa; 
15, Second phalanx; 16, Navicular bone; 17, Plantar cushion; 18, Third phalanx; 
19, Plantar surface of hoof; 20, Sensitive or keratogenous membrane of third phalanx. 



The Plantar Cushion is wedge-shaped, lying between the carti- 
lages and below the insertion of the perforans. 

The superior surface lies on the expansion of the perforans, and is 
attached by bands to the ergot, metacarpus and os pedis. The infe- 
rior surface is covered by the keratogenous membrane, and shows 
12 



7o 



EQUINE ANATOMY 



the pyramidal body moulded on the frog with its apex forward and 
two diverging arms behind. Its base terminates in two bulbs. 

The summit is attached to the plantar surface of the os pedis. 

The lateral borders are attached to the cartilages. 

Its structure is of fibrous, elastic and adipose tissue, with vessels 
and nerves. 

The Keratogenous Membrane encloses the whole of the pre- 
ceding structures, being itself enclosed by the hoof. 

It consists of the coronary cushion, velvety and laminal tissues. 




PLANTAR OR GROUND SURFACE OF A HOOF; RIGHT FOOT. 

The interval from a to a represents the toe ; From a to b, b, outside and inside quarters ; 
c, Oy Commencement of bars; d, d, Inflexions of wall at the heels, or " buttresses; " 
e, Lateral lacuna; /,/,/, Sole; g, White line ; g J ,g / , Ditto between the sole and bar ; 
h, Body of frog ; z, Branch of frog ; k, k, Glomes, or heels of frog ; /, Median lacuna. 



The Coronary Cushion resembles the derma, and forms the 
upper border of the membrane. Its inferior boundary is a white ring. 
Its superior has a margin, the perioplic ring. The extremities end 
behind in the velvety tissue. On its surface are numerous papillae. 

The Velvety Tissue is also papillary in structure, covering the 
plantar surface of the third phalanx and plantar cushion. At its cen- 
tre it is in relation with the pyramidal body and frogs, externally with 
the horny sole. 

The Lamina! (or Podophyllous) Tissue consists of 500 or 600 



VISCERAL ANATOMY. I7I 

leaves on the front and sides of the os pedis, ending below in the 
plantar cushion, each one having five or six villi lodged in depres- 
sions in the sole. The laminae have secondary folds attached to 
them at their sides. They are composed of papillary structure, like 
the remainder of the membrane, and are the principal seat of the 
tactile sense. 

The Hoof. 

The box that envelops the foot is divided into three parts, the wall, 
sole and frog. 

The wall, or crust, covers the front of the foot, and terminates 
behind by turning into the plantar cushion. Its front is called the 
toe, the sides of the toe being either the inner or outer toe, its lateral 
regions the quarters, the angle behind, where it turns into the plantar 
cushion, the heels, and these terminations the bars. 

The external surface is smooth and convex, covered by a thin, 
horny layer, the periople. 

The internal surface is continuous with the laminal tissue. 

The superior border shows depressions for the villosities of the coro- 
nary tissue. 

The inferior border is continuous with the sole, and behind is carried 
inward as the bars. 

The Sole is a thick, horny plate, forming the inferior face of the 
hoof. Its inferior face is concave, and its superior has apertures for 
the villi above it. Its outer border is continuous with the external 
surface of the wall, its inner, as the bars, lie outside the frog. 

The Prog" is V-shaped, its base behind, apex in front, separated by 
a median depression. On either side are lateral depressions ; art its 
base are two lateral elevations, the glomes. It lies between the bars 
and below the plantar cushion. 

Structure of Hoof . — Horny tissue, a modification of the epidermis. 



EQUINE PHYSIOLOGY 



Physiology is the study of the functions or actions of living 
structures or organs. 
Equine Physiology treats of its application to the horse. 



THE CIRCULATION. 

The circulatory system consists of a central organ, the heart, arter- 
ies, veins > and lymphatics (for anatomical structure see above), the 
blood and lymph. 

THE BLOOD. 

The blood, the great nutritive fluid of the body, is about ^ of the 
bodily weight in amount. 

Its composition in ioo parts venous blood — 

Corpuscles, . . . . , 32.62 

Plasma, 67.38 

100.00 

The corpuscles consist of — 

Water, 56 

Solids, 43 

99 
The plasma consists of — 

Solids, 9.16 

Water, 90.84 

100.00 
173 



174 EQUINE PHYSIOLOGY. 

The solids of plasma are — 

Fibrin, , i.oi 

Albumin, 7.76 

Fats, 12 

Extractives, 40 

Soluble salts, 64 

Insoluble salts, 17 

10.10 

The Specific Gravity of the horse's blood is 1055, its Reaction 
alkaline, and its Temperature 36.5 to 37.8 Cent. (Charles.) 

The corpuscles are found in two forms, the red and white. 

The red corpuscles are bi-concave disks, with no nuclei, tending to 
adhere in rolls, with a diameter of .005 mm. They contain the col- 
oring matter, the haemoglobin, which in the horse contains 43 per 
cent of iron, and also C. H. N. O. and S (Preyer). The haemoglo- 
bin forms about 90 per cent, of the red disks (Smith). Their function 
is to absorb and carry oxygen. 

The white corpuscles are much less numerous than the red, the pro- 
portion being on an average one white to 300 red. They are globular 
in shape and are 0.01 mm. in diameter, and contain several nuclei. 
They are derived from lymphoid tissue, and are probably developed 
into red corpuscles. They have the power of amceboid movement 
by pushing out processes and of passing through the walls of vessels. 

COAGULATION OF BLOOD. 

When blood is placed in a vessel after removal from the body, it 
goes through a process called coagulation : First, in a few minutes a 
yellow scum appears on top, the buffy coat ; second, the corpuscles 
settle to the bottom, forming a reddish layer. Then drops of serum 
are seen on the sides and top. In 12 or 15 hours the serum and clot 
are completely separated. 

The serum differs from plasma in not containing fibrin. 

The specific gravity of plasma is 1027-1028. 

Theory of Coagulation (Schmidt). 

Fibrinogen and fibrinoplas tin, with the fibrin-ferment, derived prob- 
ably from white corpuscles, come together and cause coagulation. 

Coagulation is hastened by a temperature of ioo° F., contact with 



THE CIRCULATION. I 75 

air, rough surfaces and rest, and retarded by cold, neutral salts in 
excess, exclusion of air, etc. (Brubaker). 

Arterial Blood contains more oxygen and less carbon dioxide than 
venous ; is scarlet in color, from the presence of oxy-haemoglobin. 
Venous blood is purple in color. 

The blood of the portal vein is rich in water, albuminous matter and 
sugar, and the hepatic is rich in corpuscles and sugar. 

CIRCULATION OF THE BLOOD. 

The blood may be traced from the left ventricle, through the aorta, 
to the capillaries, where it passes into the veins, being returned to the 
right auricle by the anterior and posterior cavas. From there it passes 
to the right ventricle, through the pulmonary artery, to the lungs, 
where it is oxygenated. It is then returned to the left auricle by the 
pulmonary veins, and from there to the ventricle. By this it is seen 
that the heart is the central organ of the circulation, and propels the 
blood by alternate contractions and dilatations. The contraction is 
known as the systole, the dilatation as the diastole. 

The phenomena attending the systole are a hardening, shortening, a 
movement of the apex downward, and a twisting of the heart from left 
to right. 

If the heart 's cycle is divided into ten-tenths, during the first four- 
tenths the ventricles contract simultaneously and the auricles are 
passive ; in the second four-tenths the auricles dilate and the ventricles 
are passive ; in the last two-tenths the auricles contract and the ven~ 
tricles dilate. 

The sounds of the heart are known as the first and second, with 
an interval of silence after the latter. The first sound occupies four- 
tenths, the second three-tenths, the interval of silence three-tenths. 

The first sounds longer, louder, lower in pitch and more booming 
than the second, and is caused by (1) the closing of the auriculo-ven- 
tricular valves ; (2) the apex striking against the chest ; (3) the con- 
traction of the muscular fibres ; (4) the sound of the blood passing 
through the interior. 

The second sound is shorter, higher in pitch, and clicking, and is 
caused by the closure of the mitral and tricuspid valves. 

The force of the heart, or vis a tergo, is more than sufficient to carry 
the blood through the system. 



176 EQUINE PHYSIOLOGY. 

The number of pulsations of the heart per minute are from 36 
to 40. In the newborn horse they are 120, and at the end of the first 
year from 48 to 56. 

Their relation to the respiratory movements are on an average one 
to four (the number of respiratory acts being ten per minute, usually). 

The capacity of the ventricles are each about 20 ounces. 

The entire blood in the body would pass through the left ventricle in 
66 seconds in an animal of 1000 pounds weight, assuming the amount 
of blood to be 55^ pounds ( T 2 g of the bodily weight), and requiring 
44.4 pulsations. 

Arterial Pressure is the force exerted by the blood on the vessels, 
and is measured by a tube introduced into some of the large vessels. 
In the carotid the blood pressure equals 32 mm. of mercury; in the 
brachial 150 mm. 

The Arteries may be divided into three sets (Flint), the largest 
ending at the carotid and iliacs, with elastic walls ; the median from 
these to ^ of an inch in diameter ; the smallest from -^ of an inch to 
the capillaries. The median are elastic and contractile, the smallest 
only contractile. 

The velocity of the arterial current varies in the different arteries ; it 
is the greatest during systole, least during diastole. In the carotid it 
is 300 mm. per second; in the maxillary 165 mm. per second ; meta- 
tarsal 56 mm. 

The Capillaries form the communication between the arterial and 
venous vessels, and the current of blood is much slower, only -f^ to -^ 
mm. per second, the blood pressure being only 35 mm. In the capil- 
laries the oxygen is absorbed by the tissues. 

The velocity of the venous current varies : in the jugular vein being 
100 mm., and in the vena cava no mm. per second. The blood 
pressure of the venous system is much less and the capacity much 
more than the arterial. 

Vierordt showed that 31.5 seconds after injection of a salt solution 
into one jugular, it could be detected in the vein of the opposite side. 

The valves of veins prevent damming back of blood. 

The flow of blood is kept up in the veins — 

1 st. By the vis a tergo of the heart ; 

2d. By the vis afronte or suction force of the thorax ; and 

3d. By muscular contraction on the walls of the veins. 



RESPIRATION. IJJ 

Action of the nervous system on circulation. 

The heart is under control of both the cerebro-spinal and sympa- 
thetic nervous systems, being supplied by the pneumogastric nerve 
and the cervical sympathetic, there being also probably some intra- 
cardiac sympathetic ganglia. 

The pneumogastric has an inhibitory action on the heart, as shown 
by section of the nerves, which is followed by an increased frequency 
of the heart's action. 

The sympathetic has an accelerative action on the heart, as shown 
by the previous experiment, and also by stimulation of the fibres, 
which is followed by an increased number of pulsations. Stimulation 
of the tenth nerve is followed by decreased pulsations, and if a strong 
current is used, by paralysis of the heart in diastole, by stimulation 
of its inhibitory action. 

Local circulation is regulated by the vasomotor nerves of the sym- 
pathetic system. They are known as vaso-dilators and vaso-con- 
tractors. 

RESPIRATION. 

Respiration consists of an appropriation of oxygen by the tissues 
and a giving off of carbonic oxide gas. 

The respiratory organs consist, from above downward, of the (i) 
nasal fossce, (2) pharynx, (3) larynx, (4) trachea, (5) bronchi, and (6) 
lungs. (For anatomical description, see Viscera.) 

The different steps of respiration consist — 

1st. Of the introduction of atmospheric air into the lungs in inspi- 
ration. 

2d. Of the taking up of oxygen by the blood. 

3d. Of the appropriation of oxygen by the tissues. 

4th. Of the exhalation of carbonic acid gas in expiration. ■ 

In Inspiration the air passes through the mouth or nasal cavities 
to the larynx, the glottis being dilated, then to the alveoli of the lungs, 
which it distends. 

Muscles of Inspiration. 

The diaphragm is the most important, becoming flattened, and the 
convexity decreased. 

The external intercostals and super- cos tals raise the ribs and carry 
them forward, thus enlarging the lateral diameter of the thorax. 



I78 EQUINE PHYSIOLOGY. 

In forced inspiration we have coming into action the latissimus 
dorsi, serratus anticus 7ninor and scaleni. 

In Expiration the air is forced out of the air passages, and is in a 
passive condition usually, except in forced expiration. 

The Muscles of Expiration are the diaphragm, coming forward 
in a dome-shape, decreasing the antero-posterior diameter of the 
thorax. 

The internal intercostals, triangularis sterni and serratus posticus 
minor act by carrying the ribs backward. 

In forced expiration we have coming into action the ilio-spinalis, 
external and internal oblique, transversalis and rectus of the abdom- 
inal tunic, by depressing and retracting the posterior ribs. 

Number of Respirations per Minute. 

Ordinary movements, 10 

Walking two hundred yards, 28 

Trotting five minutes, 52 

After five minutes' gallop, 52 

[Colin- Smith.) 
Capacity of the Lungs. 

In man the extreme breathing capacity of the lungs is over three 
hundred cubic inches, but the ordinary capacity is only about two 
hundred cubic inches. 

The tidal &\x is that breathed in and out in tranquil respiration. 
The reserve air is that remaining after an ordinary expiration, but 
which can be expelled in a full expiration. 

The residual air is that which always remains after a forced expi- 
ration. 

The complemental air is that which can be taken into the lungs in 
a forced inspiration. 

The measurements of the capacity of the horse's lungs are unim- 
portant, but are probably about five or six times as extensive as those 
of man. 

Changes in the Air in its Passage through the Lungs. 
Atmospheric air consists of — 

Nitrogen, 79. 15 parts. 

Oxygen, 20.81 " 

Carbon dioxide, 04 u 

100.00 



RESPIRATION. 1 79 

In its passage through the lungs it loses oxygen and gains C0 2 , 
expired air consisting of — 

Nitrogen, 79-557 

Oxygen, 16.033 

C0 2) ^ 4.38 

99.970 

The taking up of oxygen and giving off of COo takes place by the 
law of diffusion of gases, illustrated by simple experiments. That 
expired air contains C0 2 may be shown by blowing into a jar of lime- 
water, the liquid becoming turbid from the change into carbonate of 
lime, and giving off of CO L > in form of bubbles. These bubbles, when 
collected, will not support combustion, and turn blue litmus red. 

The greater part of the oxygen consumed is returned in the form 
of C0 2 , about eight out of ten parts, the remainder being thrown off 
by the urine and skin or uniting with hydrogen in the body. Solids 
and moisture in varying proportions are also thrown off. 

Changes in the Blood during* Respiration. 
Arterial blood contains in o?ie hundred parts — 

Oxygen, 20 volumes. 

Carbonic dioxide, 36 " 

Nitrogen, 1-2 " 

Venous blood contains in one hicndred parts — 

Oxygen, 8-12 volumes. 

Carbonic dioxide, 46 " 

Nitrogen, 1-2 " 

The oxygen exists in the blood in the red blood corpuscles as oxy- 
hemoglobin, being given off in the peripheral capillaries, and then is 
known as reduced hemoglobin. 

The carbon dioxide exists in serum in a loose state or as soluble 
carbonates. 

The nitrogen exists in solution in the blood serum, and can be 
expressed by a small vacuum. 

The gases compose about 60 per cent, of the volume of the blood. 

Nervous Mechanism of Respiration. 

Respiration is involuntary usually, as it is carried on during sleep 
and in unconsciousness from drugs, though it is also modified by the 
will. 



l8o EQUINE PHYSIOLOGY. 

It is under the control of the cerebro-spinal nervous system, though 
the sympathetic forms plexuses at the root of the lung. 

The respiratory centre is in the floor of the fourth ventricle, and a 
puncture at that point stops respiration immediately. If the brain is 
removed above the medulla, the act still goes on. If the carotid and 
vertebral arteries are ligated, the animal develops dyspnoea at once, 
owing to a deficiency of oxygen at the centre. The nerves of respi- 
ration are the two phrenics, two pneumogastrics, intercostals to the 
muscles of the chest, the cervical and lumbar to the muscles of the 
neck, back and abdomen. 

The Phrenics. — If the phrenics are both cut, the diaphragm is 
paralyzed; if a single one, that side only remains passive. If a sec- 
tion is made of the cord above the fifth cervical nerve, we have 
instant stopping of respiration, due to paralysis of the diaphragm and 
thoracic muscles, and immediate death. Life may be continued a 
short time after both phrenics have been divided, as the intercostal 
muscles still act. 

The Intercostals act very simply by supplying the ordinary 
muscles of expiration and inspiration. If a single one is divided, the 
remainder do its work. 

The Cervical and Lumbar nerves supply the muscles generally 
of forced inspiration and expiration. 

The Pneumogastrics. — These are distributed at the roots of the 
lungs, and if one is cut, respiration becomes very slow. Section of 
both causes marked decrease in respirations, and death in four or five 
days. A weak galvanic current applied to the nerve increases the 
number and force of the respiratory acts. Stimulation of the central 
end of its divided superior laryngeal branch causes slow respiration ; 
and if strong, paralyzes it in forced expiration. 



ALIMENTATION. 

Alimentation is the process of receiving or taking nourishment. 
It may be divided into digestion and absorption. 

Digestion is the preparation of food for absorption. 

Absorption is the process by which the digested food enters the 
circulation. 



ALIMENTATION. l8l 

Nourishment ox food is necessary to repair waste and for the growth 
of the animal. 

The food of the horse, being herbivorous, consists of the following: — 

(a) Cereals, as wheat, barley, corn, rice, and oats. They contain 
over eighty per cent, of solids, which consist of albumin, small 
amounts of fat, carbohydrates, and non-nitrogenous extractives. 
Corn and rye are rich in starch, but poor in albumin. Oats are very 
rich in starch, about fifty per cent., and also contain nine per cent, of 
albumin and six per cent, of fat. Oats also contain ferments, which 
digest starch and proteids as well as forming lactic acid ; assisting 
the stomach very materially in digestion. 

(b) Bulbs and roots, as potatoes, containing large amounts of water 
and starch ; fodder and sugar beets ; cabbages, containing a large 
amount of starch, sugar and cellulose in small amounts. 

(c) Leguminous plants, as peas and beans. 

(d) Grasses, as prairie-hay, rye-straw, grass, clover, etc. Green 
grass contains seventy-five per cent, water, clover sixty per cent. 

(e) Inorganic matter, as water, common salt, lime and potassium 
salts, and iron. 

Sodium chloride, or common salt, is essential, and regulates endos- 
mosis and exosmosis. Other salts are deposited in bone. The iron 
forms the coloring matter of the blood. 

The Amount of Food Required. 

The horse needs daily 7500 grammes of hay and 2270 of oats, or 
10 kilo (22 lbs.) of hay, and 2 kilo (4.4 lbs.) of oats to every 100 kilo 
(220 lbs.) of body weight. Colin says that the horse will eat 26 kinds 
of plants and reject 212 (Meade-Smith). 

It should receive daily about two per cent, of its body weight in 
solid food, and should be in the proportion of 1 to 4 of nitrogenous 
and non-nitrogenous material. The different steps of digestion are 
prehension, mastication, salivary digestion, deglutition, gastric and 
intestinal digestion, absorption and defecation, or expulsion from the 
body of the residue not required for alimentation. 

PREHENSION. 

Prehension is the process of transferring the food to the mouth, 
and is the first or primary act of digestion. 

The upper lip carries the food to the teeth, the long neck and head 



1 82 



EQUINE PHYSIOLOGY 



being carried to the ground, the head then makes a quick movement 
to the side, and the food is carried to the side of the mouth to be 
ground up by the molars (see Teeth). 

Liquid may be taken in by (a) sucking; in the young, (b) pumping by 
piston action of tongue ; (c) aspiration, by an inspiratory movement. 
The second one is the most often used by the horse. 



MASTICATION. 

Mastication is a complex act in which the food is triturated in the 
mouth between the two jaws and teeth. (For anatomical considera- 
tions, see Teeth.) 

Movements of the Jaws. 

In the horse these are depression, elevation and rotation, and in 
mastication make eighty strokes per minute. The incisors serve to 
bite off a portion of food, which is then, by the tongue and muscles 
of the face, carried between the molars, where it is comminuted to a 
much greater degree. 



The Time of the Appearance of the Teeth. 

Meade-Smith, from Kreutzer. 





ERUPTION. 


CHANGE. 


Incisors : — 






Central, . . 


Before or few days 
after birth. 


2 years. 


Middle, . . 
Outer,. . . 


4 to 6 weeks. 
6 to 9 months. 


3 l /2 years. 
4^ years 


Canines, . . 
Molars : — 


4 to 5 years. 




I, .... 


Before or few days 
after birth. 


2 /^ years. 


2, .... 


Before or few days 
after birth. 


2. l / 2 years. 


3, .... 


Before or few days 
after birth. 


3 years. 


4, .... 


io to 12 months 


3 years. 


5, .... 


I ]/ 2 to 2 years. 


3 years. 


6, .... 


4 to 5 years. 


3 years. 



ALIMENTATION*. 1 83 

SALIVARY DIGESTION. 

For anatomical considerations, see Mouth, 

Saliva is alkaline in reaction, its specific gravity is 1004.5, and its 
amount in 24 hours is 84 pounds. Its composition (Meade Smith, 
from Lassaigue) is as follows for mixed saliva — 

Water, 992.00 

Mucus and albumin, 2.00 

Carbonates, 1.0S 

Chlorides, 4.92 

Phosphates etc., traces. 

1000.00 

It also contains epithelium, mucin, pytalin, serum, albumin, globu- 
lin and sulpho-cyanide of potassium. 

The parotid saliva is the largest in amount and most watery. 

The sub-maxillary is viscid and contains no albumin, and the sub- 
lingual is very viscid and contains a large amount of solids. 

Action of the Saliva. — It has a 7necha?iical action, by lubricating the 
bolus of food, and a chemical by the action of its ferment, ptyalin. 
This converts starch into sugar, and cane sugar into grape sugar. As 
this process takes several minutes, it continues going on in the 
stomach. 

DEGLUTITION. 

The act of deglutition consists of the passage of the food from the 
mouth to the stomach ; it is divided into three stages ; the first stage 
comprises the passage of the bolus from the mouth, through the fauces 
to the pharynx ; the second, its passage through the pharynx, and the 
third when it passes through the oesophagus. 

In the first stage, the tip, body and base of the tongue press against 
the hard palate, and push the bolus along toward the pharynx, the 
teeth being closed. The palato-glossi and phary?igei then contract 
and force the bolus into the pharynx, the palatal curtain being carried 
against the superior pharyngeal wall. 

In the second stage the constrictors contract, the epiglottis closes 
the top of the larynx, and the bolus is passed into the oesophagus. 

In the third stage the oesophagus contracts on the bolus, and by 



1 84 EQUINE PHYSIOLOGY. 

the movement of its circular and longitudinal fibres forces it through 
the cardiac orifice of the stomach into that viscus. 

The first stage is voluntary, the others involuntary. 

The horse can make from 65 to 90 motions of deglutition per min- 
ute for fluids. 

GASTRIC DIGESTION. 
From the difficulty or impossibility of making a gastric fistula in 
the horse, the amount and composition of the gastric juice is hard to 
estimate. Its specific gravity is about 1010, its reaction acid and its 
composition is as follows — 

{Water, ^ 

Hydrochloric acid, . . . V 982.80 

Lactic acid, j 

Solids, 17.20 

1000.00 

The solids are — 

Pepsin, 

Milk-curdling ferment, 

Chlorides, 

Phosphates, 

Iron. 

The amount of acids vary from 0.084 P er cent, to 0.2 per cent. 
The juice from the fundus of the stomach contains more ferment, 
more acid and more mucus than that from the pylorus. 

Action of the G-astric Juice. 

The gastric juice changes starch into sugar, not of itself, but by the 
saliva, which still continues its action, converts vegetable albumin 
into peptones, and digests cellulose by fermentation to some extent. 
In feeding the horse the food should be taken in the following order : 
first water, second hay, third oats, as the water if given last would 
wash the food into the intestine before it was acted upon by the gastric 
juice, while if hay was given after oats, it would carry them along 
with it as it is principally digested in the intestines, the oats being 
acted upon by the stomach for the most part. The stomach is never 
completely empty, as some food remains after 24 hours. 



ALIMENTATION. 1 85 

Vomiting in the horse is very infrequent and difficult, on account of 
there being no dilatation of the stomach at the point where the ceso-, 
phagus enters, the oesophagus being very narrow at its termination 
and being nearly filled by folds of its mucous membrane. 

It takes place by a deep inspiration, forcing the diaphragm down 
and fixing it ; then a relaxation of the oesophageal orifice with a spas- 
modic contraction of the abdominal muscles, completes the act. 



THE BILE. 

The bile, secreted by the liver, acts upon the food in the upper part 
of the small intestine. It is brownish-green in color, alkaline in 
action, bitter in taste. Its specific gravity is higher than the gastric 
and lower than the pancreatic juice, and its amount in 24 hours is 
from 11 to 13^ pounds. 

Its composition is as follows : — 

Water. 
Mucin. 

{ Glycocholate of Soda. 

(_ Taurocholate of Soda. 

_.. . f Bilirubin. 

Bile coloring matter "<_,... ,. 
b ( Bihverdin. 

Cholesterin. 
Iron and salts. 

The Mucin comes from the biliary passages, not from the liver 
cells. 

Gmelin's Test for Biliary Pigment. 

Spread a drop of diluted bile on a porcelain plate and add a drop 
of yellow nitric acid to it. A play of colors results, green, blue, vio- 
let and yellow. (Charles.) 

Pettenkofer's Test for Biliary Acids. 

Add a little sugar to the fluid, then shake and add a few drops of 
strong sulphuric acid. A beautiful purple or violet coloration will 
appear. 

Cholesterin is excreted by the liver, and is derived from broken- 
down nerve-tissue. Under the microscope it appears as delicate, thin, 
flattened, super-imposed plates, with one corner broken off. 
13 



1 86 EQUINE PHYSIOLOGY. 

Action of the Bile in Digestion. 

i. It dissolves and emulsifies fats and liberates fatty acids in small 
amounts. 

2. It acts as a stimulus to peristalsis by its irritant action on the 
intestinal mucous membrane. 

3. It prevents decomposition of fseces, the fseces being colored by 
the bile pigments in the form of hydro-bilirubin. 

4. It is said to contain a ferment in small amount, capable of con- 
verting starch into sugar. 

Glycogenic Function. 

From observation it has been found that the liver has another func- 
tion — the changing of the carbohydrates and albumin into a new 
substance, glycogen, C 6 H 10 O 5 , whitish in color, inodorous, amorphous, 
insoluble in alcohol or ether, but imperfectly soluble in boiling water 
(Charles). It is taken up in the form of glucose, then stored up as 
glycogen, and then changed into glucose again, when it is carried 
away from the liver. 

Uses of Glycogen. — It is probably burned up in the lungs, circulation 
and muscles in generating animal heat, and in muscular action. 

Puncture of the floor of the medulla causes glycosuria, as shown by 
Bernard. An animal deprived of bile by a fistula dies of starvation 
after losing four-tenths of its bodily weight. 



THE PANCREATIC JUICE. 

The secretion of the pancreas is colorless and alkaline in reaction. 
It is coagulated by heat, metallic salts, tannic acid, etc. ; is easily 
decomposed, emitting an offensive odor. Its specific gravity is about 
1020, and amount in 24 hours is about 12^ pounds. Its composition 
is as follows : — 

Water, 982.05 

Organic matter, %.%% 

Ash, 8.59 

The ash consists of phosphates, chlorides, iron and magnesium. 
The organic matter consists of four ferments — an amylolytic, a pro- 
teolytic, one acting on fats, and a milk-curdling ferment. 

The first may be extracted by a solution of arseniate of potassium 



ALIMENTATION. 1 87 

with a little ammonia added ; the second by potassium iodide, and 
the third by a solution of bicarbonate of soda with a little caustic soda. 

Action of the Pancreatic Juice. 

1. It changes starch and glucose into sugar rapidly and completely. 
Cane-sugar not acted upon. 

2. It emulsifies and saponifies fats completely with the aid of the 
bile. 

3. It converts albumin into peptones. 

4. It, by means of a special ferment, curdles milk. This ferment 
can be extracted by a solution of common salt, but has not yet been 
isolated in the horse. 

THE INTESTINAL JUICE. 

This is secreted by Brunner's glands and the crypts of Lieberkuhn. 
Its specific gravity is about 1010; alkaline in reaction, and its compo- 
sition is as follows (Charles, from Colin) : — 

Water, 98.10 

Solids, 1.90 

Albumin and other organic matters, 0.45 

Carbonate of soda, 1.45 



Its amount in 24 hours is difficult to estimate, Colin having found 
about 12 ounces an hour in about six feet of gut. This may be in- 
creased by injection into the gut of irritants. 

Its Action is much the same as the pancreas, dissolving proteids 
and albumin, and converting starch into sugar. 

The gases found in the intestine are oxygen, nitrogen, carbon 
dioxide, hydrogen, ammonia, carburetted and sulphuretted hydrogen. 
About 60 per cent, of the proteids have to be digested in the small 
intestine. 

DIGESTION IN THE LARGE INTESTINE. 
The Caecum serves as a reservoir for the food after about 24 hours, 
the fermentative changes of the small intestine still going on in an 
alkaline medium. About 20 per cent, of the food is digested in that 
viscus, and about 40 per cent, of the cellulose. 



1 88 EQUINE PHYSIOLOGY. 

The Colon acts principally as an absorbing area, the food passing 
through its several curvatures and the floating colon before reaching 
the rectum. The diaphragmatic curvature contains large amounts 
of fluid. 

THE FAECES. 

The residue of aliment after digestion is expelled from the rectum 
in rounded balls as faeces. Horses defecate every three hours, and 
will pass about 17 kilos or 37.4 pounds, or 5.8 of solids. 

About 13 per cent, are inorganic materials. 



DEFECATION. 
Defecation is the process of evacuation of the rectum. The pre- 
sence of fecal matter in the rectum leads to the desire to expel it. 
The brain then sends an inhibitory action to the reflex centre in the 
lumbar cord, which causes a relaxation of the sphincter muscles. 
Contraction of the abdominal muscles and small colon, with the 
circular fibres of the rectum, then take place, causing a propulsion 
of the faeces through the anus. The mucous membrane of the open- 
ing is everted, then pulled back by the retractor muscles. 

INTESTINAL MOVEMENTS. 

The food is carried along by peristalsis, a worm-like motion of the 
intestine due to involuntary contraction of both the longitudinal and 
circular muscular fibres. The irritation of the bile is an active factor 
in keeping it up. 

ABSORPTION. 

Absorption is the process of taking up the food principles after 
digestion, also water and salts that have not been acted upon. It 
takes place by means of lymphatics and veins. 

By Veins. — The water, salts, sugar, soaps and peptones are absorbed 
quickly by osmosis, and also by some special function of the epithelial 
cells of the villi. 

By Lymphatics. — This takes place by the villi (see Intestines} ; the 
emulsified food elements passing into their interior by the intercellular 
connective tissue, then by the lymph channels of the mesentery to 



ABSORPTION. 189 

the receptaculum. Lymph is an alkaline, viscid fluid of a specific 
gravity of about 1030; its amount in 24 hours, 72 kilos or 158 pounds. 
Its composition is (Smith, from C. Schmidt) — 

Water, 9 6 3-93 

Solids, 36.07 

1000.00 

Solids are — 

Fibrin, ~\ 

Albumin, K 28.84 

Fats, etc., J 

Inorganic salts, 7.22 

36.06 

It contains lymph corpuscles, identical with white blood corpuscles 
in structure. 

The course of the lymph is from the various lymphatics of the peri- 
phery to the receptaculum, then through the thoracic duct into the 
confluence of the jugulars. Chyle is lymph during digestion, and 
contains emulsified fats in addition to its usual composition. It passes 
through the villi to the thoracic duct. Its composition (Charles, from 
Schmidt) is — 

Serum, 96.74 

Clot, 3.25 

Water, ^Z.^j 

Solids, 1 1.2 

Solids are — 

Fats, 0.15 

Soaps, 0.03 

Fibrin, 3.89 

Albumin, sugar, etc., 6.59 

Hoematin, salts, 

After a meal the chyle is very abundant, during fasting very small 
in amount. The flow of lymph is kept up by the contraction of their 
walls, by the aspiration of the diaphragm, contraction of the abdo- 
minal muscles, and the peristalsis of the intestines. 



I90 EQUINE PHYSIOLOGY. 

ANIMAL HEAT. 
The process of nutrition and oxidation of food products is accom- 
panied by the evolution of heat. This gives the body an average 
temperature which, in the horse, varies between 37. 5 C. and 38 C. 

Sources of Animal Heat. 

This is the result of oxidation of the hydrocarbons and carbo- 
hydrates as well as the combination of hydrogen and oxygen forming 
water. 

Heat Units. — The English heat unit is the amount of heat requisite 
to raise one pound of water, i° F. In the horse, for each kilo of 
weight, 2.1 heat units are set free per hour, or for an animal of 500 
kilos, as an example, 1050 heat units per hour, or in a day 2.1 X 500 
X 24 = 25,200 heat units. In a man of 140 pounds, 13,440 heat units 
are thrown off in the same time. 

The temperature is raised by exercise, due to increased tissue meta- 
bolism, and the urea is increased. 

The temperature of the blood of the portal vein is usually several 
degrees higher than the average temperature of the body. 



SECRETION. 

Secretion (Flint) is the act by which fluids holding certain principles 
in solution are separated from the blood, or are manufactured by 
special organs from materials furnished by the blood. These have a 
function to perform. 

An Excretion contains elements not formed in the substance of 
the gland, which have no function to perform and are extracted from 
the blood. 

There are always two periods in every secreting organ — 

1st, The period of repose, or period of no secretion; though the 
manufacture of the solid elements is constantly going on. 

2d, The period of functional activity \ in which the formed elements 
are washed out by the water from the blood, which is eight times as 
abundant in this stage. 

Classes of secreting organs. 

1. The most simple is abasement membrane covered with flattened 
cells, as the peritoneum. 



ABSORPTION. I9I 

2. The next is more secreting surface with not much more space, as 
the simple depressions of Lieberkiihn in the small intestines. 

3. The second variety have two or more branches leading into a 
common duct, as in Brunner's glands. 

4. Where a number of the third variety open into a common duct, 
the compound racemose glands, as the salivary and pancreatic glands. 

5. Tubular glands composed of a number of elongated tubes, as in 
the testicle and kidney. 

6. The ductless glands, as the spleen and supra-renal capsules. 

7. Unclassified glands, as the liver. 

The Permanent fluids are the aqueous and vitreous humors of the 
eye, sy?tovial, serous, cerebrospinal and fluid of the internal ear. 

The Transitory fluids are mucus, cerumen, sebaceous matter, Meibo- 
mian, tears, milk and all the digestive fluids. 

The Excretions are the urine, sweat, fceces, and bile, which is also a 
secretion in part. 

THE PERSPIRATION. 

(For anatomy of skin, see Sense of Touch.) 

The perspiration is of low specific gravity, about 1004, alkaline or 
neutral in reaction and contains about 2 per cent, of solids, consisting of 
urea, fats, cholesterin and salts. Its amount varies with exercise and 
in different parts of the body, being most abundant in the inguinal 
region. When it is secreted in small amounts not to be seen by the 
eye it is called insensible, when in large amounts, sensible perspiration. 

Its fimctions are the regulation of animal heat and also excretion 
of urea, etc. 

Section of the cervical sympathetic increases the secretion in that 
part, and certain drugs, as Jaborandi, have a like action. 

The Sebaceous matter of the skin consists of about y water and y$ 
solids, of albumin, epithelium, fat, soaps and salts. 

It acts as a lubricant to the skin and hair. 

THE MAMMARY SECRETION. 
Milk is secreted soon after the birth of the foal, obtained by suction, 
is alkaline in reaction and of a specific gravity of about 1030. It 
consists of (Charles, from Gorup-Besanez) — 

Water, 82.84 

Solids, 17.16 

100.00 



I92 EQUINE PHYSIOLOGY. 

Casein, ) i 

Albumin, j 

Butter, 6.87 

f* sugar 1 8.6 S 

Inorganic salts, j . 

17.16 

The gases of milk (Pfliiger) are carbonic anhydride, oxygen and 
nitrogen. 

Colostrum is the milk secreted a short time after parturition. It 
is yellow in color, of a higher specific gravity, slightly acid, contains 
large oil globules covered with casein, and has purgative properties. 

The mammae at the time of gestation become enlarged, pendent, 
soft. The epithelium becomes rounded, and contains a large amount 
of fat. 

Milk can be coagulated by acids, tannin and mineral salts by co- 
agulating the casein. 

Mare's milk contains a large amount of sugar, which, by the addition 
of an acid, takes on a lactic acid fermentation, as in the preparation of 
koumiss. 

The rapidity and amount of the mammary secretion are depend- 
ent on arterial pressure. Certain drugs have more or less action 
upon it. 

URINE. 
Urine, the excretion of the kidneys, is a watery, yellowish fluid, 

holding in suspension many solids, which are excreted in this form. 

It is alkaline in reaction when the animal feeds on vegetable food, 

and its specific gravity varies from 1016 to 1060, usually about 1050. 

Its composition is (Smith, from Boussingault) — 

Urea, 31. 

Potass, hippurate, 4.7 

Alkaline lactates, 20.1 

Potass, bicarb., 155 

Magn. carb., 4.2 

Calcium carb., 10.8 

Potass, sulph., 1.2 

Sodium chloride, 0.7 

Silica, 1.0 

Water, 910.0 

1000.0 



ABSORPTION. I93 

Mucin is abundant. The urea is dependent on the amount of oats, 
grain and roots ingested, the hippuric acid (C 9 H 9 N0 3 ), to which and 
phenol the odor is due, on the amount of green stuff, hay and straw. 

The amount in twenty-four hours is five or six litres, varying with 
the amount of fluid excreted by the sweat glands. 

The secretion of urine takes place — 

1. By filtration, the water and soluble salts passing out into the 
interior of the glomerulus. 

2. By active secretion, urea being excreted by the epithelial cells of 
the convoluted tubules. The latter process has been proved by inject- 
ing indigo car?ni?ie into the blood after section of the spinal cord to 
prevent filtration. The carmine can be found in the cells of the 
convoluted tubes, and also in the urine, none being found in the 
glomerulus. 

Urine is decreased in summer, due to the increased amount of 
secretion by the skin, by slowing the heart, by sleep and rest. 

It is increased by cold weather, stimulation of the heart, after eating, 
and also by stimulation of the medulla. 

After secretion, the urine passes into the pelvis of the kidney, 
through the ureter, drop by drop, into the bladder, where it is accumu- 
lated till discharged, the bladder being emptied three or four times in 
twenty-four hours. 

Nervous mechanism of micturition. 

The centre for micturition is located in the lumbar enlargement of 
the cord. The sensation of fullness is carried to this centre, which 
sends back an impulse, relaxing the contracted sphincter, and causing 
a contraction of the longitudinal (or detrusor) fibres. This forces the 
contents into the urethra, the contraction of its fibres terminating the 
act. 

After section of the spinal cord, a condition known as retentio?i with 
overflow takes place, the bladder is distended, and soon also the 
sphincter vesicce by mechanical means, the urine escaping drop by 
drop and soon becoming ammoniacal. 



THE DUCTLESS GLANDS. 
These are the spleen, see Abdo?nen; the thyroid and thymus, see 
Thorax; and the supra-renal capsules, see Kidney. 

The Supra-renal Capsules are relatively larger before birth, 



194. EQUINE PHYSIOLOGY. 

can be extirpated with no apparent result, are probably connected 
in some way with the sympathetic system, but their function is not 
known. 

The Spleen probably influences digestion, and Sniff and Herzon 
claim that the secretion of trypsin, one of the pancreatic ferments, is 
dependent on it: 

In its structure are found pigment, broken-down red blood cor- 
puscles and many leucocytes. It also serves as a reservoir for the 
abdominal circulation. It can be removed without loss of life, and is 
a blood gland. 

The Thyroid and Thymus have to do with the elaboration of 
blood, otherwise their function is unknown. 

The Pituitary Body and Conarium also properly belong in 
this category, but their function is unknown. 



THE NERVOUS SYSTEM. 

The nervous system connects into a coordinated organism all parts 
of the body. It receives all impressions, regulates all movements, 
voluntary and involuntary, and the functions of secretion, nutrition, 
calorification and all processes of animal life. (Flint.) The cerebro- 
spinal sy 'stem consists of the brain, cord and the various nerves, and 
presides over animal life. The sympathetic presides over nutrition 
or organic life. 

(For structure of nerves, see Anatomy of Nervous System.) 

Terminations of nerves. 

To voluntary muscular fibres the nerve divides and" spreads out 
into plaques. 

To involuntary fibres, it loses its tubular membrane and terminates 
in the nucleus as the axis cylinder. 

The Sensory nerves terminate — 

(a) As minute plexuses with no fixed arrangement. 

(b) As the tactile corpuscles or end bulbs of Krause % found most 
abundantly in the lip, hoof, sheath and glans penis. These are 
small capsules of connective tissue, the nerve terminating in a 
plexus or bulbous extremity. They have also a central termination 
either in the brain or cord, connected to a cell pole by an axis 



THE NERVOUS SYSTEM. 1 95 

cylinder. After its origin a nerve does not inosculate but passes to 
its terminus. 

Nerves are divided into motor and sensory, the former ending in 
muscles and conducting the stimulus by which the muscle acts, the 
latter carrying sensation from the periphery to the centre. 

Nerves act as conductors, but do not produce anything. 

A nerve's function is manifested at its terminus. 

Xerve stimulation can be accomplished mechanically, chemically 
or thermically, also by a mild current of electricity. 

Rate of nervous conduction is 250 feet per second (electrotonus, for 
lack of space, will not be described). 

The Spinal nerves are 42 or 43 in number, arranged in pairs (for de- 
scription, see Nerves). The superior or sensory nerves end in the 
superior or sensory horns of the gray matter of the cord, the inferior 
or motors end in the inferior or motor horns. Stimulation of the 
former causes pain at its peripheral distribution, and section loss of 
sensation at the same point. Stimulation of the latter causes contrac- 
tion of the muscles to which it is supplied, and section motor paralysis 
of the same. 

THE CRANIAL NERVES. 
The First or Olfactory will be discussed under Smell. • 

The Second or Optic terminates in the retina, the fibres decus- 
sating. 

Section of one tract before decussation, causes total blindness of 
the outer half of the eye of the same side and the inner half of the 
opposite. Injuries of the visual centre produce the same result. 

The Third or Oculo-motor is entirely motor, and supplies all 
the muscles of the eye, except the external rectus, great oblique and 
part of the posterior rectus, the pupil with contractility and move- 
ments of the ciliary muscle. Section causes external strabismus, 
ptosis, dilatation of the pupil, and inability to rotate the globe in a 
vertical direction. 

The Fourth or Patheticus is entirely motor and paralysis causes 
inability to rotate the eye laterally. 

The Fifth or Trifacial is a mixed nerve, viz., both sensory and 
motor. The ophthalmic and superior maxillary branches are entirely 
sensory, the inferior maxillary both sensory and motor. Division of 



I96 EQUINE PHYSIOLOGY. 

the nerve in front of the Gasserian ganglion causes loss of sensation 
in its course and also trophic changes in the eyeball, the latter not 
taking place if the section is made behind the ganglion, by leaving 
the sympathetic attachments intact. Stimulation causes exquisite 
pain, as it is the most sensitive nerve in the body. Section of the in- 
ferior maxillary branch causes paralysis of the muscles of mastication 
on the same side, and loss of sensation in one lateral half of the 
tongue. Stimulation causes a spasm of the same muscles. 

The Sixth or Abducens is purely motor, and, if cut, we have an 
inability to carry the eye outward. 

The Seventh or Facial is motor, and also sends the chorda 
tympani as a special nerve of taste to the anterior two-thirds of the 
tongue. 

Section causes paralysis of the superficial muscles of the face, 
stapedius, occipito-styloid, digastric, stylo-hyoid, subcutaneous muscle 
of the neck and soft palate, through the great petrosal to Meckel's 
ganglion. There is also loss of taste on the anterior two-thirds of the 
tongue of the same side. 

Stimulation causes contraction of the same muscles. 

The Eighth or Auditory is a nerve of special sense purely. 
Section produces deafness on the same side. 

The Ninth or Glosso-pharyngeal is a mixed nerve, being one 
of general sensation to the pharynx and fauces, of special sense of 
taste to the back part of the tongue, and of motion to the pharyngeal 
muscles in part. It is concerned obviously in deglutition. 

The Tenth or Pneumogastric. 

The auricular branch gives sensation to the external ear. 

The pharyngeal give sensation to pharynx and to muscles con- 
cerned in deglutition. 

If the superior laryngeal branch is stimulated, spasm of the glottis 
and diaphragm results. 

If the inferior laryngeal is cut, an arrest of the respiratory move- 
ments of the glottis takes place, as it supplies all the muscles of the 
larynx except the crico-thyroid. 

Cardiac Bra?iches. — If the nerve is cut in tfce neck, its inhibitory 
action on the heart is taken off and it is increased in frequency. 
Galvanization of the peripheral end decreases its action and stops it 
in diastole, if strong enough. 



THE NERVOUS SYSTEM. I97 

Pulmonary Branches. — If the nerves are cut in the neck, the respi- 
rations are markedly diminished, death finally occurring. Galvani- 
zation increases the number ; if strong, may arrest it. 

Oesophageal Branches. — Paralysis of these cause an inability to 
swallow food, which remains in the gullet. It is finally vomited by 
irritation of the tube. 

Gastric Branches. — If the left nerve is cut during digestion, secre- 
tion and motion at once cease ; slightly irritated, it causes glycosuria. 

After division, the bile becomes more fluid in character, the forma- 
tion of glycogen ceases, and purgatives have no longer any effect. 

Eleventh or Spinal Accessory. 

This is a motor nerve as well as supplying the larynx through the 
laryngeals. 

Stimulation causes spasm of the sterno-maxillaris, mastoido-hwner- 
alis and cervical and dorsal trapezius. 

Division causes paralysis of these as well as shortness of breath, 
from incoordination of muscles and inability to make a prolonged 
vocal sound. 

Twelfth or Hypoglossal. 

This is purely motor, and division causes paralysis of the muscles 
of the tongue and difficulty in mastication and deglutition. 



THE SPINAL CORD. 

The inferior or motor roots emerge from the larger extremity of the 
horn of gray matter on either side, and communicate with the large 
multipolar motor cells found in groups in that situation. 

The superior or sensory roots enter the cord, immediately commu- 
nicating with the tripolar sensory cells of the smaller extremity of the 
gray matter, which comes to the surface. 

Some of both the motor and sensor)' roots enter the columns of the 
opposite side or lateral tracts, not all of the fibres thus passing up or 
down at the same point. 

Decussation of motor and sensory tracts. 

Most of the motor nerves cross to the opposite side at the medulla, 
the nerves from the right side of the brain ending on the left side of 
the body, and vice versa. Some of the motor roots continue down 
the cord on the same side as the direct pyrajnidal tract. 



I98 EQUINE PHYSIOLOGY. 

The sensory nerves decussate all along the cord, not at one fixed 
point, ending at the sensory portion of the internal capsule and hippo- 
campus major. Thus one side of the brain governs the sensation of 
the opposite side. 

Functions of the Cord. 

I. As a conductor . II. As an independent nerve centre. 

I. As a Conductor. — The inferior and inferior lateral columns con- 
vey motor impulses from the brain to the periphery. If a section of 
both motor tracts is made, motor paralysis will result below that point. 
If one tract, motor paralysis on the same side only. 

If the sensory portion of the cord is cut completely, a similar 
absence of sensation below that point and inability to coordinate will 
be the result. If a unilateral sensory section is made, there will be 
complete loss of sensation on the opposite side. 

Section of one lateral half of the cord causes motor paralysis on 
the same side, with hyperesthesia and sensory paralysis on the other. 

II. As a Nerve Centre. — If a frog is decapitated and placed in a 
vacuum it will remain quiet. Now, if its surface is irritated, muscular 
contractions will result. If the cord is broken up no such phenomena 
take place, showing that the cord controlled these movements, which 
are called reflex actions. The sensory nerves convey the impression 
to a centre in the cord, which send it back to the muscles, causing a 
contraction (Flint). 

The gray substance of the cord is neither sensible nor excitable. 
The inferior lateral white columns are excitable throughout, but not 

sensible. 

The superior columns are sensible, more so at the entrance of the 

posterior nerve-roots. They are not excitable. Deeply, they are 

neither excitable nor se7isible. 



THE ENCEPHALON. 

The encephalon consists of the inedulla oblongata, pons, corpora 
striata, corpora quadrigemina, optic thalami, olfactory lobes, ce?'ebellum 
and cerebrum. 

MEDULLA OBLONGATA. 

This serves as a medium of transjnission of motor and sensory im- 
pulses, and also as the centre for numerous functions, as mastication, 
deglutition, vo7iiiting, a cardiac centre, a vaso?notor centre and a 



THE NERVOUS SYSTEM. 1 99 

respiratory centre. The glycositric centre has been already referred 
to (see Liver). 

PONS VAROLII. 

The superficial fibres are not excitable or sensible ; the deeper are 
excitable, and the posterior are only sensible. It presides over volun- 
tary motion and sensation. 

CORPORA STRIATA. 

Electrical stimulation of one of these causes general muscular con- 
traction on the opposite side. Destruction of the internal capsule 
causes loss of motion and sensation on the opposite side of the body. 
The anterior part of the internal capsule is motor, the posterior sensory. 

CORPORA QUADRIGEMINA. 

These are situated in the path of visual conduction, and are con- 
nected with the sense of sight and reflex movements of the iris. 

OPTIC THALAMI. 

These are probably connected with sensation, vision and complex 
muscular actions, though their function is not thoroughly understood. 

OLFACTORY LOBES. 

These are the centres for the special sense of smell, and their de- 
struction causes a loss of this sense. Fibres have been traced to the 
uncinate gyrus, temporo-sphenoidal region and optic thalami. 

CEREBELLUM. 

The cerebellum presides over the coordination of movements of 
progression, being connected intimately with the superior column of 
the cord. Their destruction leads to absence of coordination. 

CEREBRUM. 

The cerebral hemispheres are the centres of intellect or mind, receiv- 
ing impressions and giving off impulses. An animal deprived of the 
cerebrum retains the special senses of sight, sound, taste, etc., but 
the intellectual faculties are all lost. From experimentation on the 
lower animals and by observation in disease, centres have been located 
which preside over certain functions. 

The motor area is located in the cortex above the fissure of Sylvius 



200 EQUINE PHYSIOLOGY. 

and at the junction of the anterior with the middle third of the sur- 
face. The upper part presides over the hinder extremity of the oppo- 
site side, the middle over the anterior extremity, and the lower over 
the face. In front of the latter in man is found the speech centre on 
the left side. 

The centre for sight is located in the occipital region ; those for 
smell, hearing and taste in the temporo-sphenoidal region. 

THE SYMPATHETIC SYSTEM. 

This chain of twenty-eight ganglia is sensible after long stimulation. 

After section of the cord in the neck, there is increased vascularity 
by paralyzing the coats of the small vessels. 

Functions. — It influences the general process of nutrition and forms 
the vasomotor system. This sends branches to small blood-vessels, 
and influences local circulation by vaso-dilaiors and vaso-coniractors. 



SPECIAL SENSES. 

TOUCH. 

When a foreign body is brought into contact with the surface, it is 
appreciated by the nerves of the part as the special sense of touch. 

This sense is located in the skin and also on mucous membranes 
for a certain distance. The termination of nerves in the skin has 
been already noticed. In the horse, with a single digit covered with 
hard material, the hoof is an imperfect organ of touch, but can 
estimate solidity and resistance. 

The lip is a well-marked tactile organ, the end bulbs of Krause 
being very abundant. 

SMELL. 

The sense of smell is very acute in the horse. It has already been 
sufficiently considered under the anatomical description. 

TASTE. 
Taste enables the animal to detect the flavor of substances. The 
anterior two-thirds of the tongue preside over the ability to recognize 
acids and alkalies, and is supplied by the chorda tympani of the 



SPECIAL SENSES. 201 

seventh, the posterior one-third, recognizing bitters and sweets, being 
supplied by the glossopharyngeal nerve. The circumvallate or 
calyciform papillae are probably gustatory, the other papillae serving 
to entangle substances, so that their flavor can be detected. 

HEARING. 

The External Ear collects the sound waves and carries them 
inward to the membrana tympani. 

The Middle Ear. 

The membrana tympani receives the sound waves and transmits 
them through the ossicles to the foramen ovale opening into the 
vestibule. 

The Eustachian tube allows air to enter the tympanum, and thus 
equalizes the pressure on both'sides of the membrana tympani. The 
guttural pouch, at its termination below, is probably connected with 
phonation. 

The Internal Ear. 

The semicircular canals have some function connected with main- 
taining equilibrium. 

The organs of Corti are probably the essential parts of the internal 
ear, and here the sound waves are recognized, each sound by a 
separate organ, the organs receiving the waves by vibrations of the 
endolymph transmitted from the perilymph. 

SIGHT. 

Sight is the special sense by which we are enabled to form an idea 
of objects by means of the eye. 

Mechanism. 

The rays of light enter the eye by passing through the cornea, 
aqueous humor, pupil, crystalline lens and vitreous to the retina, 
where they are recognized and the impression sent to the brain by 
the optic nerve. 

The function of the cornea, aqueous, and lens is to refract the rays 
of light and bring them to a focus on the retina. 

The iris regulates the amount of light entering the eye by means 
of its muscular fibres dilating and contracting the pupil. 

The retina receives the impression of light, the layer of rods and 
H 



202 EQUINE PHYSIOLOGY. 

cones being the most sensitive portion. The point of entrance of the 
optic nerve is known as the blind spot. 

Accommodation. 

When an object is distant, the rays of light are more parallel, less 
refraction is necessary, and the lens is flattened. When the object is 
near, the opposite condition holds, the lens becoming convex by con- 
traction of the ciliary muscle ; this decreasing the intra-ocular pres- 
sure and allowing the lens to increase in thickness. In the ordinary 
condition the intra-ocular pressure on the suspensory ligament of the 
lens retains it in a flattened state. 

Space need not, obviously, be given to errors of refraction and 
accommodation. 

REPRODUCTION. 

For discussion of copulation and development of the embryo, see 
works on Veterinary Obstetrics and Embryology. 



INDEX. 



Abdomen, 123. 
Absorption, 188. 
Anatomy, 9. 
Angeiology, 81. 
Animal heat, 190. 
Anus, 128. 
Aorta, anterior, 85. 

common, 85. 

posterior, 93. 

thoracic, 93. 
Arterial pressure, 176. 
Arteries, structure of, 85. 
Artery, anterior radial, 87. 
tibial, 97. 

axillary, 85. 

collateral of cannon, 88. 

common carotid, 89. 
interosseous, 88. 

external carotid, 91. 
iliac, 96. 

femoral, 96. 

humeral, 87. 

internal carotid, 91. 
iliac, 96. 

pedal, 98. 

popliteal, 97. 

posterior radial, 87. 
tibial, 97. 

pulmonary, 98. 

spermatic, 95. 
Arthrology, 37. 
Articulations, 37. 

of anterior extremity, 41. 

classes of, 37. 

hyoid, 40. 

of lower jaw, 39. 

of posterior extremity, 45. 

structure of, 38. 

thoracic, 40. 

vertebral, 38. 



Bile, action of, 186. 

amount of, 185. 

composition of, 185. 

tests for, 185. 
Bladder, 144. 
Blood, amount of, 173. 

coagulation of, 174. 

composition of, 173. 

gases in arterial, 179. 
venous, 179. 

plasma of, 173. 



Bone, hyoid, 24. 

number of, 10. 

structure of, 10. 
Bones of anterior extremity, 25. 

face, 18. 

head, 13. 

pelvis, 31. 

posterior extremity, 31. 

thorax, 24. 

varieties of, 9. 

vertebral column, 11. 
Brain (see Cerebrura). 

membranes of, 105. 
Bronchi, 138. 



Caecum, 128. 

digestion in, 187. 
Cerebellum, 107. 

function of, 199. 
Cerebrum, 105. 

fissures of, 107. 

functions of, 199. 

lobes of, 108. 

ventricles of, 109. 
Chyle, composition of, 189. 
Circulation, 175. 

nervous mechanism of, 177. 
Colon, large, 128. 

small, 128. . 
Concha, 157. 
Corpora quadrigemina, 106. 

function ot, 199. 
Cowper's glands, 148. 



Defecation, 188. 

nervous mechanism of, 1S8. 
Deglutition, 183. 

stages of, 183. 
Digestion, 180. 

in large intestine, 187. 
Digestive system, 120. 
Ductless glands, 140. 

function of, 193. 
Duodenum, 125. 



Ear, 157. 

external, 157. 

canal of, 159. 
cartilages of, 157. 
muscles of, 158. 



203 



204 



INDEX. 



Ear, internal, 161. 

middle, 159. 
Epididymis, 146. 
Eustachian tube, 160. 
Excretion, 190. 
Expiration, 178. 

changes of air in, 178. 

muscles of, 178. 
Eye, appendages of, 166. 

blood supply of, 167. 

function of, 201. 

humors, 162. 

muscles of globe of, 165: 
lids of, 165. 

tunics of, 162. 



Fseces, 188. 

amount of, 188. 
Fluids, permanent, 191. 

transitory, 191. 
Food, 181. 

amount of, required, 181. 

Gastric juice, action of, 184. 

amount of, 184-. 

composition of, 184. 
Guttural pouches, 160. 

Hair, 168. 

Hearing, 201. 

Heart, blood supply of, 84. 

cavities of, 83. 

diastole of, 175. 

nerve supply of, 84. 

number of pulsations of, 176. 

sounds of, 175. 

systole of, 175. 

valves of. 83, 84. 

weight of, 81. 
Heat units, number of, 190. 
Hoof, 168. 
Hymen, 151. 

Ileum, 125. 

Inspiration, muscles of, 177. 
Intestinal juice, action of, 186. 
composition of, 187. 
movements, 188. 
Isthmus, parts of, 106. 

Jejunum, 125. 

Kidneys, 141. 

function of, 192. 
hilum of, 141. 
Malpighian bodies of, 141. 
pelvis of, 141. 

Larynx, 133. 

cartilages of, 133. 
ligaments of, 134. 
movements of, 177. 
muscles of, 135. 
nerve supply of, 136. 



Liver, 129. 

fissures of, 129. 

glycogenic function of, 186. 

ligaments of, 129. 

lobes of, 129. 

parenchyma of, 129. 
Lungs, 138. 
Lymph, amount of, 189. 

composition of, 189. 
Lymphatic duct, 103. 

glands, 102. 
Lymphatics, 102. 



Malpighian corpuscles, 143. 
Mammary glands, 155. 

function of, 191. 
Mastication, 182. 
Mastoid cells, 159. 
Mediastinal, 140. 
Medulla oblongata, 105. 

function of, 198. 
Membrana tympani, 159. 
Micturition, mechanism of, 193. 
Milk, composition of, 191. 
Mouth, 120. 
Muscles, appendages of, 50. 

of abdomen, 65. 

of anterior extremity, 66. 

of back, 63. 

of ear, 158. 

of eye, 165. 

of face, 51. 

of foot, 7?. 

of hyoid, 54. 

of inferior cervical region, 57. 

of leg, 77. 

of mastication, 53. 

of palate, 55. 

of pelvis, 72. 

of perineum, 150. 

of pharynx, 56. 

of tail, 80. 

of thigh, 75. 

of thorax, 63. 

of tongue, 55. 

of trunk, 57. 

structure of, 50. 

varieties of, 50. 
Myology, 50. 



Nasal fossae., 155. 
Nerve, abducens, 113. 

auditory, 113. 

facial, 113. 

glosso-pharyngeal, 113. 

hypo-glossal, 114. 

oculo-motor, 111. 

olfactory, 111. 

optic, 111. 

patheticus, 111. 

pneumogastric, 114. 

spinal accessory, 114. 

tri-facial, 112. 

ganglia of, 111. 
Nerves, brachial plexus of, 115. 

cervical, 115. 



INDEX. 



205 



Nerves, cranial, function of, 195. 

dorsal, 118. 

lumbo-sacral plexus of, 117. 

structure of, 103. 

terminations of, 103. 
Nervous system, 103. 

divisions of, 103. 
structure of, 103. 
Neurology, 103. 
Nostrils, 156. 

(Esophagus, 122.' 

Olfactory lobes, function of, 199. 

Optic thalami, 107. 

Orbits, 162. 

Ossicles of tympanum, 160. 

Ovaries, 153. 

Oviducts, 153. 

Palate, 120. 
Pancreas, 131. 

Pancreatic juice, action of, 186. 
amount of, 186. 
composition of, 186. 
Pericardium, 81. 
Perineum, 150. 
Peritoneum, 132. 

reflections of, 133. 

structure of, 133. 
Penis, 149. 
Perspiration, 191. 

function of, 191. 
Peyer's glands, 127. 
Pharynx, 122. 
Physiology, 173. 
Pineal gland, 107. 
Pituitary gland, 107. 
Pleura, 139. 
Pons varolii, 106. 

function of, 199. 
Prehension, 181. 
Prostate gland, 148. 



Receptaculum chyli, 103. 
Rectum, 128. 
Reflex action, 198. 
Reproduction, 202. 
Respiration, 177. 

nervous mechanism of, 179. 

number of movements of, 178. 
Respiratory organs, 133. 



Saliva, 183. 

amount of, 183. 

composition of, 183. 

function of, 183. 
Salivary glands, 122. 

structure of, 122. 
varieties of, 122. 
Schneiderian membrane, 156. 
Secretion, 190. 
Sight, 201. 
Sinuses of dura, 99. 
Skin, 167. 

glands of, 168. 



Skull, fossae of, 23. 
Small intestine, 125. 
Smell, 200. 
Spinal cord, 103. 

columns of, 104 
fissures of, 104. 
function of, 98. 
membranes of, 104. 
Spleen, 132. 

function of, 194. 
Stomach, 123. 

capacity of, 123. 
coats of, 123. 
glands of, 125. 
Supra-renal capsules, 144. 

function of, 193. 

Sympathetic nervous system, 11J 

function of, 193. 

Taste, nerves of, 157. 

papillae of, 157. 
Teeth, 120. 

action of, 182. 

structure of, 121. 

varieties of, 121. 
Testicles, 145. 

descent of, 146. 

function of, 147. 
Thoracic duct, 103. 
Thorax, 140. 
Thymus, 141. 

function of, 194. 
Thyroid, 140. 

function of, 194. 
Tongue, 120. 
Touch, 200. 
Trachea, 136. 
Tunica vaginalis testis, 145. 

Ureters, 144. 
Urethra, female, 151. 

male, 148. 
Urinary organs, 141. 
Urine, 192. 

composition of, 192. 
Uriniferous tubes, 143. 
Uterus, 152. 

Vagina, 151. 
Valve, pyloric, 124. 

of Vieussens, no. 
Valvulae conniventes, 127. 
Vas deferens, 147. 
Veins, jugular, 99. 

of abdomen, 101. 

of anterior extremity, 99. 

of head and neck, 99. 

of posterior extremity, 102. 

portal, 101. 

pulmonary, 102. 

saphenous, 102. 
Vesiculae seminales, 147. 
Villi, 127. 
Viscera, 120. 
Vulva, 150. 

bulbs of, 151. 



CATALOGUE No. 7. 



JULY, 1890. 



A CATALOGUE 

OF 

BOOKS FOR STUDENTS. 



INCLUDING THE 



? QUIZ-COMPENDS ? 



CONTENTS. 




PAGE 




PAGE 


New Series of Manuals, 2,3,4,5 


Obstetrics. . 


. 10 


Anatomy, 


6 


Pathology, Histology 


. 11 


Biology, 


11 


Pharmacy, . 


. 12 


Chemistry, . 


6 


Physiology, . 


. 11 


Children's Diseases, 


7 


Practice of Medicine, 


. 12 


Dentistry, 


8 


Prescription Books, 


. 12 


Dictionaries, 


8 


?Quiz-Compends ? 


• 14, 15 


Eye Diseases, 
Electricity, . . m . 


8 


Skin Diseases, 


. 12 


9 


Surgery, 


• 13 


Gynaecology, 


10 


Therapeutics, 


. 9 


Hygiene, 


9 


Urine and Urinary Or 


gans, 13 


Materia Medica, . 


• 9 


Venereal Diseases, 


• J 3- 


Medical Jurisprudence, 


10 







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6 STUDENTS' TEXT-BOOKS AND MANUALS. 

ANATOMY. 

Macalister's Human Anatomy. 816 Illustrations. A new 
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graphical, including the Embryology, Histology and Morphology 
of Man. With special reference to the requirements of 
Practical Surgery and Medicine. With 816 Illustrations, 
400 of which are original. Octavo. Cloth, 7.50; Leather, 8.50 

Ballou's Veterinary Anatomy and Physiology. Illustrated. 
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Holden's Anatomy. A manual of Dissection of the Human 
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suggestive, giving more at a glance than pages of text description. 
* * * The text matches the illustrations in directness of prac- 
tical application and clearness of detail." — New York Medical 
Record. 

Holden's Human Osteology. Comprising a Description of the 
Bones, with Colored Delineations of the Attachments of the 
Muscles. The General and Microscopical Structure of Bone and 
its Development. With Lithographic Plates and Numerous Illus- 
trations. Seventh Edition. 8vo. Cloth, 6.00 

Holden's Landmarks, Medical and Surgical. 4th ed. Clo., 1.25 
Heath's Practical Anatomy. Sixth London Edition. 24 Col- 
ored Plates, and nearly 300 other Illustrations. Cloth, 5.00 

Potter's Compend of Anatomy. Fourth Edition. 117 Illus- 
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CHEMISTRY. 

Bartley's Medical Chemistry. Second Edition. A text-book 
prepared specially for Medical, Pharmaceutical and Dental Stu- 
dents. With 50 Illustrations, Plate of Absorption Spectra and 
Glossary of Chemical Terms. Revised and Enlarged. Cloth, 2.50 

Trimble. Practical and Analytical Chemistry. A Course in 
Chemical Analysis, by Henry Trimble, Prof, of Analytical Chem- 
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Edition. 8vo. Cloth, 1.50 

J$&~ See pages 2 to 3 for list of Students' Manuals. 



STUDENTS' TEXT-BOOKS AND MANUALS. 7 

Chemistry : — Continued. 

Bloxam's Chemistry, Inorganic and Organic, with Experiments. 
Seventh Edition. Enlarged and Rewritten. 330 Illustrations* 

Cloth, 4.50 ; Leather, 5.50 

Richter's Inorganic Chemistry. A text-book for Students. 
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Prof. Edgar F. Smith, ph.d. 89 Wood Engravings and Colored 
Plate of Spectra. Cloth, 2.00 

Richter's Organic Chemistry, or Chemistry of the Carbon 
Compounds. Illustrated. Cloth, 3.00 ; Leather, 3.50 

Symonds. Manual of Chemistry, for the special use of Medi- 
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Physician Roosevelt Hospital, Out-Patient Department; Attend- 
ing Physician Northwestern Dispensary, New York. i2mo. 

Cloth, 2.00; Interleaved for Notes, 2.40 

Tidy. Modern Chemistry. 2d Ed. Cloth, 5.50 

Leffmann's Compend of Chemistry. Inorganic and Organic. 
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Muter. Practical and Analytical Chemistry. Second Edi- 
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Holland. The Urine, Common Poisons, and Milk Analysis, 
Chemical and Microscopical. For Laboratory Use. 3d 
Edition, Enlarged. Illustrated. Cloth, 1.00 

Van Nuys. Urine Analysis. Illus, Cloth, 2.00 

Wolff's Applied Medical Chemistry. By Lawrence Wolff, 
m.d., Dem. of Che^mistry in Jefferson Medical College. Clo., 1.00 

CHILDREN. 

Goodhart and Starr. The Diseases of Children. Second 
Edition. By J. F. Goodhart, m.d., Physician to the Evelina 
Hospital for Children; Assistant Physician to Guy's Hospital, 
London. Revised and Edited by Louis Starr, m.d., Clinical 
Professor of Diseases of Children in the Hospital of the Univer- 
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Hatfield. Diseases of Children. By M. P. Hatfield, m.d., 
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Day. On Children. A Practical and Systematic Treatise. 
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4S5*- See Pages 14 and IS for list 0/ ? Quiz-Compends ? 



3 STUDENTS' TEXT-BOOKS AND MANUALS. 

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Meigs and Pepper. The Diseases of Children. Seventh 
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Starr. Diseases of the Digestive Organs in Infancy and 
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DENTISTRY. 

Fillebrown. Operative Dentistry. 330 Illus. Cloth, 2.50 

Flagg's Plastics and Plastic Filling. 3d Ed. Preparing. 

Gorgas. Dental Medicine. A Manual of Materia Medica and 
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Harris. Principles and Practice of Dentistry. Including 
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Richardson's Mechanical Dentistry. Fifth Edition. 569 
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Stocken's Dental Materia Medica. Third Edition. Cloth, 2.50 

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Talbot. Irregularities of the Teeth, and their Treatment. 
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DICTIONARIES. 

Gould's New Medical Dictionary. Containing the Definition 
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Tables etc. y 2 Dark Leather, 3.25 ; y 2 Mor., Thumb Index 4.25 
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Cleaveland's Pocket Medical Lexicon. 31st Edition. Giving 

correct Pronunciation and Definition. Very small pocket size. 

Cloth, red edges .75 ; pocket-book style, 1.00 

Longley's Pocket Dictionary. The Student's Medical Lexicon, 
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cine, with an Appendix giving Poisons and Their Antidotes, 
Abbreviations used in Prescriptions, Metric Scale of Doses, etc. 
24mo. Cloth, 1. 00; pocket-book style, 1.25 

4&=- See pages 2 to 5 for list 0/ Students' Manuals. 



STUDENTS' TEXT-BOOKS AND MANUALS. 9 

EYE. 

Arlt. Diseases of the Eye. Including those of the Conjunc- 
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Arlt. Translated by Dr. Lyman Ware. Illus. 8vo. Cloth, 2.50 

Hartridge on Refraction. 4th Ed. Cloth, 2.00 

Meyer. Diseases of the Eye. A complete Manual for Stu- 
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Fox and Gould. Compend of Diseases of the Eye and 
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ELECTRICITY. 

Mason's Compend of Medical and Surgical Electricity. 

With numerous Illustrations. i2mo. Cloth, 1.00 

HYGIENE. 

Parkes' (Ed. A.) Practical Hygiene. Seventh Edition, en- 
larged. Illustrated. 8vo. Cloth, 4.50 

Parkes' (L. C.) Manual of Hygiene and Public Health. 
i2mo. Cloth, 2.50 

Wilson's Handbook of Hygiene and Sanitary Science. 
Sixth Edition. Revised and Illustrated. Cloth, 2.75 

MATERIA MEDICA AND THERAPEUTICS. 

Potter's Compend of Materia Medica, Therapeutics and 

Prescription Writing. Fifth Edition, revised and improved. 

Cloth, 1.00; Interleaved for Notes, 1.25 

Biddle's Materia Medica. Eleventh Edition. By the late 
John B. Biddle, m.d., Professor of Materia Medica in Jefferson 
Medical College, Philadelphia. Revised, and rewritten, by 
Clement Biddle, m.d., Assist. Surgeon, U. S. N., assisted by 
Henry Morris, m.d. 8vo., illustrated. Cloth, 4.25; Leather, 5.00 

Headland's Action of Medicines. 9th Ed. 8vo. Cloth, 3.00 

Potter. Materia Medica, Pharmacy and Therapeutics. 
Including Action of Medicines, Special Therapeutics, Pharma- 
cology, etc. Second Edition. Cloth, 4.00; Leather, 5,00 

Starr, Walker and Powell. Synopsis of Physiological 
Action of Medicines, based upon Prof. H. C. Wood's " Materia 
Medica and Therapeutics." 3d Ed Enlarged. Cloth, .75 

Waring. Therapeutics. With an Index of Diseases and 
Remedies. 4th Edition. Revised. Cloth, 3.00; Leather, 3.50 

&&* See pages 14 and 13 for list 0/ ? Quiz- Comp ends ? 



10 STUDENTS' TEXT-BOOKS AND MANUALS. 

MEDICAL JURISPRUDENCE. 

Reese. A Text-book of Medical Jurisprudence and Toxi- 
cology. By John J. Reese, m.d., Professor of Medical Juris- 
prudence and Toxicology in the Medical Department of the 
University of Pennsylvania ; President of the Medical Juris- 
prudence Society of Philadelphia ; Physician to St. Joseph's 
Hospital ; Corresponding Member of The New York Medico- 
legal Society. 2d Edition. Cloth, 3.00; Leather, 3.50 

Woodman and Tidy's Medical Jurisprudence and Toxi- 
cology. Chromo-Lithographic Plates and 116 Wood engravings. 

Cloth, 7.50; Leather, 8.50 

OBSTETRICS AND GYNECOLOGY. 
Byford. Diseases of Women. The Practice of Medicine and 
Surgery, as applied to the Diseases and Accidents Incident to 
Women. By W. H. Byford, a.m., m.d., Professor of Gynaecology 
in Rush Medical College and of Obstetrics in the Woman's Med- 
ical College, etc., and Henry T. Byford, m.d., Surgeon to the 
Woman's Hospital of Chicago ; Gynaecologist to St. Luke's 
Hospital, etc. Fourth Edition. Revised, Rewritten and En- 
larged. With 306 Illustrations, over 100 of which are original. 
Octavo. 832 pages. Cloth, 5.00 ; Leather, 6.co 

Cazeaux and Tarnier's Midwifery. With Appendix, by 

Munde. The Theory and Practice of Obstetrics ; including the 
Diseases of Pregnancy and Parturition, Obstetrical Operations, 
etc. By P. Cazeaux. Remodeled and rearranged, with revi- 
sions and additions, by S. Tarnier, m.d., Professor of Obstetrics 
and Diseases of Women and Children in the Faculty of Medicine 
of Paris. Eighth American, from the Eighth French and First 
Italian Edition. Edited by Robert J. Hess, m.d., Physician to 
the Northern Dispensary, Philadelphia, with an appendix by 
Paul F. Munde, m.d., Professor of Gynaecology at the N. Y. 
Polyclinic. Illustrated by Chromo-Lithographs, Lithographs, 
and other Full-page Plates, seven of which are beautifully colored, 
and numerous Wood Engravings. Students' Edition. One 
Vol., 8vo. Cloth, 5.00; Leather, 6.00 

Lewers' Diseases of Women. A Practical Text-Book. 139 
Illustrations. Second Edition. Cloth, 2.50 

Parvin's Winckel's Diseases of Women. Second Edition. 

Including a Section on Diseases of the Bladder and Urethra. 
15c Illustrations. Revised. See page 3. 

Cloth, 3.00; Leather, 3.50 

Morris. Compend of Gynaecology. Illustrated. In Press. 

Winckel's Obstetrics. A Text-book on Midwifery, includ- 
ing the Diseases of Childbed. By Dr. F. Winckel, Professor 
of Gynaecology, and Director of the Royal University Clinic for 
Women, in Munich. Authorized Translation, by J. Clifton 
Edgar, m.d., Lecturer on Obstetrics, University Medical Col- 
lege, New York, with nearly 200 handsome illustrations, the 
majority of which are original with this work. Octavo. 

Cloth, 6.00; Leather, 7.00 

Landis' Compend of Obstetrics. Illustrated. 4th edition, 
enlarged. Cloth, 1.00; Interleaved for Notes, 1.25 

4^" See Pages 2 to 5 for list of New Manuals. 



STUDENTS' TEXT-BOOKS AND MANUALS. 11 

Obstetrics and Gynecology : — Continued. 
Galabin's Midwifery. By A. Lewis Galabin, m.d., f.r.c.p. 
227 Illustrations. See page 3. Cloth, 3.00; Leather, 3.50 

Glisan's Modern Midwifery. 2d Edition. Cloth, 3.00 

Rigby's Obstetric Memoranda. 4th Edition. Cloth, .50 

Meadows' Manual of Midwifery. Including the Signs and 

Symptoms of Pregnancy, Obstetric Operations, Diseases of the 

Puerperal State, etc. 145 Illustrations. 494 pages. Cloth, 2.00 

Swayne's Obstetric Aphorisms. For the use of Students 

commencing Midwifery Practice. 8th Ed. i2mo. Cloth, 1.25 

PATHOLOGY. HISTOLOGY. BIOLOGY. 

Bowlby. Surgical Pathology and Morbid Anatomy, for 
Students. 135 Illustrations. i2mo. Cloth, 2.00 

Davis' Elementary Biology. Illustrated. Cloth, 4.00 

Gilliam's Essentials of Pathology. A Handbook for Students. 
47 Illustrations. i2mo. Cloth, 2.00 

***The object of this book is to unfold to the beginner the funda- 
mentals of pathology in a plain, practical way, and by bringing 
them within easy comprehension to increase his interest in the study 
of the subject. 

Gibbes* Practical Histology and Pathology. Third Edition. 

Enlarged. i2mo. Cloth, 1.75 

Virchow's Post-Mortem Examinations. 2d Ed. Cloth, i.co 

PHYSIOLOGY. 

Yeo's Physiology. Fourth Edition. The most Popular Stu- 
dents' Book. By Gerald F. Yeo, m.d., f.r.c.s., Professor of 
Physiology in King's College, London. Small Octavo. 758 
pages. 321 carefully printed Illustrations. With a Full 
Glossary and Index. See Page 3. Cloth, 3.00; Leather, 3.50 

Brubaker's Compend of Physiology. Illustrated. Fifth 
Edition. Cloth, 1.00; Interleaved for Notes, 1.25 

Stirling. Practical Physiology, including Chemical and Ex- 
perimental Physiology. 142 Illustrations. Cloth, 2.25 

Kirke's Physiology. New 12th Ed. Thoroughly Revised and 
Enlarged. 502 Illustrations. Cloth, 4.00; Leather, 5.00 

Landois' Human Physiology. Including Histology and Micro- 
scopical Anatomy, and wiih special reference to Practical Medi- 
cine. Third Edition. Translated and Edited by Prof. Stirling. 
692 Illustrations. Cloth, 6.50; Leather, 7.50 

" With this Text-book at his command, no student could fail in 

his examination." — Lancet. 

Sanderson's Physiological Laboratory. Being Practical Ex- 
ercises for the Student. 350 Illustrations. 8vo. Cloth, 5.00 

Tyson's Cell Doctrine. Its History and Present State. Illus- 
trated. Seeond Edition. Cloth, 2.00 

jGE^* See pages 14 and 15 for list of ? Quiz-Compends ? 



12 STUDENTS' TEXT-BOOKS AND MANUALS. 



PRACTICE. 

Taylor. Practice of Medicine. A Manual. By Frederick 
Taylor, m.d., Physician to, and Lecturer on Medicine at, Guy's 
Hospital, London ; Physician to Evelina Hospital for Sick Chil- 
dren, and Examiner in Materia Medica and Pharmaceutical 
Chemistry, University of London. Cloth, 4.00 

Roberts' Practice. New Revised Edition. A Handbook 
of the Theory and Practice of Medicine. By Frederick T. 
Roberts, m.d. ; m.r.c.p., Professor of Clinical Medicine and 
Therapeutics in University College Hospital, London. Seventh 
Edition. Octavo. Cloth, 5.50 ; Sheep, 6.50 

Hughes. Compend of the Practice of Medicine. 4th Edi- 
tion. Two parts, each, Cloth, 1.00; Interleaved for Notes, 1.25 

Part x. — Continued, Eruptive and Periodical Fevers, Diseases 
of the Stomach, Intestines, Peritoneum, Biliary Passages, Liver, 
Kidneys, etc., and General Diseases, etc. 

Part ii. — Diseases of the Respiratory System, Circulatory 
System and Nervous System ; Diseases of the Blood, etc. 

Physician's Edition. Fourth Edition. Including a Section 
on Skin Diseases. With Index. 1 vol. Full Morocco, Gilt, 2.50 

Tanner's Index of Diseases, and Their Treatment. Cloth, 3.00 

PRESCRIPTION BOOKS. 

Wythe's Dose and Symptom Book. Containing the Doses 
and Uses of all the principal Articles of the Materia Medica, etc. 
Seventeenth Edition. Completely Revised and Rewritten. Just 
Ready. 321110. Cloth, 1.00; Pocket-book style, 1.25 

Pereira's Physician's Prescription Book. Containing Lists 
of Terms, Phrases, Contractions and Abbreviations used in 
Prescriptions Explanatory Notes, Grammatical Construction of 
Prescriptions, etc., etc. By Professor Jonathan Pereira, m.d. 
Sixteenth Edition. 32mo. Cloth, 1. 00; Pocket-book style, 1.25 

PHARMACY. 

Stewart's Compend of Pharmacy. Based upon Remington's 
Text-Book of Pharmacy. Second Edition, Revised. 

Cloth, 1. 00 ; Interleaved for Notes, 1.25 

SKIN DISEASES. 

Anderson, (McCall) Skin Diseases. A complete Text-Book, 
with Colored Plates and numerous Wood Engravings. 8vo. 
Just Ready. Cloth, 4.50; Leather, 5.50 

Van Harlingen on Skin Diseases. A Handbook of the Dis- 
eases of the Skin, their Diagnosis and Treatment (arranged alpha- 
betically). By Arthur Van Harlingen, m.d., Clinical Lecturer 
on Dermatology, Jefferson Medical College; Prof, of Diseases of 
the Skin in the Philadelphia Polyclinic. 2d Edition. Enlarged. 
With colored and other plates and illustrations. i2mo. Cloth, 2.50 

Bulkley. The Skin in Health and Disease. By L. Duncan 
Bulkley, Physician to the N. Y. Hospital. Illus. Cloth, .50 

4®=* See pages 2 to 5 for list of New Manuals. 



STUDENTS' TEXT-BOOKS AND MANUALS. 13 

SURGERY. 

Caird and Cathcart. Surgical Handbook for the use of 
Practitioners and Students. By F. Mitchell Caird, m b., 
f.r.c.s., and C. Walker Cathcart, m.b., f.r.c.s., Asst. Sur- 
geons Royal Infirmary. With over 200 Illustrations. 400 pages. 
Pocket size. Leather covers, 2.50 

Jacobson. Operations in Surgery. A Systematic Handbook 
for Physicians, Students and Hospital Surgeons. By W. H. A. 
Jacobson, b.a., Oxon. f.r.c.s. Eng. ; Ass't Surgeon Guy's Hos- 
pital ; Surgeon at Royal Hospital for Children and Women, etc. 
199 Illustrations. 1006 pages. 8vo. Cloth. 5.00; Leather, 6.00 

Heath's Minor Surgery, and Bandaging. Ninth Edition. 142 
Illustrations. 60 Formulas and Diet Lists. Cloth, 2.00 

Horwitz's Compend of Surgery, including Minor Surgery, 
Amputations, Fractures, Dislocations, Surgical Diseases, and the 
Latest Antiseptic Rules, etc., with Differential Diagnosis and 
Treatment. By Orville Horwitz, b.s., m.d., Demonstrator of 
Surgery, Jefferson Medical College. 3d edition. Enlarged and 
Rearranged. 91 Illustrations and 77 Formulae. i2mo. 

Cloth, 1. co ; Interleaved for the addition of Notes, 1.25 

Walsham. Manual of Practical Surgery. For Students and 
Physicians. By Wm. J. Walsham, m.d., f.r.c.s., Asst. Surg, 
to, and Dem. of Practical Surg, in, St. Bartholomew's Hospital, 
Surgeon to Metropolitan Free Hospital, London. With 236 
Engravings. See Page 2. Cloth, 3.00; Leather, 3.50 

URINE, URINARY ORGANS, ETC. 

Acton. The Reproductive Organs. In Childhood, Youth, 
Adult Life and' Old Age. Seventh Edition. Cloth, 2.00 

Beale. Urinary and Renal Diseases and Calculous Disorders. 
Hints on Diagnosis and Treatment. i2mo. Cloth, 1.75 

Holland. The Urine, and Common Poisons and The 
Milk. Chemical and Microscopical, for Laboratory Use. Illus- 
trated. Third Edition. i2mo. Interleaved. Cloth, 1.00 

Ralfe. Kidney Diseases and Urinary Derangements. 42 Illus- 
trations. i2mo. 572 pages. Cloth, 2.75 

Legg. On the Urine. A Practical Guide. 6th Ed. Cloth, .75 

Marshall and Smith. On the Urine. The Chemical Analysis of 
the Urine. By John Marshall, m.d., Chemical Laboratory, Univ. 
of Penna; and Prof. E. F. Smith, ph.d. Col. Plates. Cloth, 1.00 

Thompson. Diseases of the Urinary Organs. Eighth 
London Edition. Illustrated. Cloth, 3.50 

Tyson. On the Urine. A Practical Guide to the Examination 
of Urine. With Colored Plates and Wood Engravings. 6th Ed. 
Enlarged. i2mo. Cloth, 1.50 

Bright's Disease and Diabetes. Illus. Cloth, 3.50 

Van Nuys, Urine Analysis. Illus. Cloth, 2.00 

VENEREAL DISEASES. 

Hill and Cooper. Student's Manual of Venereal Diseases, 
with Formulae. Fourth Edition. i2mo. Cloth, 1.00 

Durkee. On Gonorrhoea and Syphilis. Illus. Cloth, 3.50 
4^* See pages 14 and 13 for list of ? Quiz- Comp ends ? 



NEW AND REVISED EDITIONS. 

?gUIZ-COMPENDS? 

The Best Compends for Students' Use 
in the Quiz Class, and when Pre- 
paring for Examinations. 

Compiled in accordance with the latest teachings of promi- 
nent lecturers and the most popular Text-books. 

They form a most complete, practical and exhaustive 
set of manuals, containing information nowhere else col- 
lected in such a condensed, practical shape. Thoroughly 
up to the times in every respect, containing many new 
prescriptions and formulae, and over two hundred and 
fifty illustrations, many of which have been drawn and 
engraved specially for this series. The authors have had 
large experience as quiz-masters and attaches of colleges, 
with exceptional opportunities for noting the most recent 
advances and methods. 

Cloth, each $1.00. Interleaved for Notes, $1.25. 

No. 1. HUMAN ANATOMY, "Based upon Gray." Fourth 
Edition, including Visceral Anatomy, formerly published 
separately. Over 100 Illustrations. By Samuel O. L. 
Potter, m.a., m.d., late A. A. Surgeon U. S. Army. Professor 
of Practice, Cooper Medical College, San Francisco. 

Nos. 2 and 3. PRACTICE OF MEDICINE. Fourth Edi- 
tion. By Daniel E. Hughes, m.d., Demonstrator of Clinical 
Medicine in Jefferson Medical College, Philadelphia. In two parts. 
Part I. — Continued, Eruptive and Periodical Fevers, Disease* 
of the Stomach, Intestines, Peritoneum, Biliary Passages, Liver, 
Kidneys, etc. (including Tests for Urine), General Diseases, etc. 

Part II. — Diseases of the Respiratory System (including Phy- 
sical Diagnosis), Circulatory System and Nervous System; Dis- 
eases of the Blood, etc. 

*** These little books can be regarded as a full set of notes upon 
the Practice of Medicine, containing the Synonyms, Definitions, 
Causes, Symptoms, Prognosis, Diagnosis, Treatment, etc., of each 
disease, and including a number of prescriptions hitherto unpub- 
lished. 

No. 4. PHYSIOLOGY, including Embryology. Fifth 
Edition. By Albert P. Brubaker, m.d., Prof, of Physiology, 
Penn'a College of Dental Surgery ; Demonstrator of Physiology 
in Jefferson Medical College, Philadelphia. Revised, Enlarged 
and Illustrated. 

No. 5. OBSTETRICS. Illustrated. Fourth Edition. By 
Henry G. Landis, m.d., Prof, of Obstetrics and Diseases of 
Women, in Starling Medical College, Columbus, O. Revised 
Edition. New Illustrations. 



BLAKISTOX'S ? QUIZ-COMPEXDS ? 

Continued. 

Bound in Cloth, $1.00. Interleaved, for Notes, $1.25 

No. 6. MATERIA MEDICA, THERAPEUTICS AND 
PRESCRIPTION WRITING. Fifth Revised Edition. 
With especial Reference to the Physiological Action of Drugs, 
and a complete article on Prescription Writing. Based on the 
Last Revision of the U. S. Pharmacopoeia, and including many 
unofficinal remedies. By Samuel O. L. Potter, m.a., m.d., 
late A. A. Surg. U. S. Army; Prof, of Practice, Cooper Medical 
College, San Francisco. Improved and Enlarged, with Index. 

No. 7. GYNECOLOGY. A Compend of Diseases of Women. 
By Henry Morris, m.d., Demonstrator of Obstetrics, Jefferson 
Medical College, Philadelphia. 

No. 8. DISEASES OF THE EYE AND REFRACTION, 

including Treatment and Surgery. By L. Webster Fox, m.d., 
Chief Clinical Assistant Ophthalmological Dept., Jefferson Med- 
ical College, etc., and Geo. M. Gould, m.d. 71 Illustrations, 39 
Formulae. Second Enlarged and Improved Edition. Index. 

No. 9. SURGERY. Illustrated. Third Edition. Including 
Fractures, Wounds, Dislocations, Sprains, Amputations and 
other operations; Inflammation, Suppuration, Ulcers, Syphilis, 
Tumors, Shock, etc. Diseases of the Spine, Ear, Bladder, Tes- 
ticles, Anus, and other Surgical Diseases. By Orville Horwitz, 
a.m., m.d., Demonstrator of Surgery, Jefferson Medical Col- 
lege. Revised and Enlarged. 77 Formulas and 91 Illustrations. 

No. 10. CHEMISTRY. Inorganic and Organic. For Medical 
and Dental Students. Including Urinary Analysis and Medical 
Chemistry. By Henry Leffmann, m.d., ProL of Chemistry in 
Penn'a College of Dental Surgery, Phila. Third Edition, Revised 
and Rewritten, with Index. 

No. 11. PHARMACY. Based upon " Remington's Text-book 
of Pharmacy." By F. E. Stewart, m.d., ph. g., Quiz-Master 
at Philadelphia College of Pharmacy. Second Edition, Revised. 

No. 12. VETERINARY ANATOMY AND PHYSIOL- 
OGY. 29 Illustrations. By Wm. R. Ballou, m.d., Prof, of 
Equine Anatomy at N. Y. College of Veterinary Surgeons. 

No. 13. DISEASES OF CHILDREN. By Dr. Marcus P. 
Hatfield, Prof, of Diseases of Children, Chicago Medical 
College. 

Bound in Cloth, $1. Interleaved, for the Addition of Notes, $1.25. 



These books are constantly revised to keep up with 
the latest teachings and discoveries, so that they contain 
all the new methods and principles. No series of books 
are so co?nplete in detail, concise in language, or so well 
printed and bound. Each one forms a complete set of 
notes upon the subject under consideration. 

Descriptive Circular Free. 



NOW READY. 



A NEW 

MEDICAL 

DICTIONARY 

BY GEORGE M. GOULD, 

Ophthalmic Surgeon, Philadelphia Hospital, etc. 



AN ENTIRELY NEW BOOK. 
Based On Recent Medical Literature. 



Small Octavo. 320 Pages. Handsomely Printed. 

Bound in Half Dark Leather, $3.25. 

Half Morocco, Thumb Index, $4.25. 



SEND FOR SPECIAL CIRCULAR. 



Medical Students 5 Handbooks. 

BARTLEY'S MEDICAL CHEMISTRY. A Text-book for Medical 
and Pharmaceutical Students. By E. H. Bartley, m.d., Professor of 
Chemistry and Toxicology at the Long Island College Hospital ; President 
of the American Society of Public Analysts ; Chief Chemist, Board of 
Health, of Brooklyn, N. Y. With Illustrations, Glossary, and Complete 
Index. i2mo. Cloth, #2.50. 

M Probably the best chemistry for medical students."— Journal of the American Medi- 
cal Association. 

" I especially like the first part, dealing with chemical physics and elementary chemistry." 
—Pro/. J. W. Hoi land, Jefferson Medical College, Phila. 

VAN HARLINGEN ON SKIN DISEASES. Their Diagnosis and 
Treatment. By Arthur Van Harlingen, m.d., Prof, of Diseases of the 
Skin in the Philadelphia Polyclinic ; Lecturer on Dermatology, Jefferson 
Medical College. With Lithographic Plates and other Illustrations. 
Second Edition. Enlarged. 410 pages. l2mo. Cloth, #2.50. 

*£* This is a complete epitome of skin diseases, arranged in alphabetical 
order, giving the diagnosis and treatment. Many prescriptions are given that 
have never been published in any text-book, and an article incorporated on 
Diet. The plates do not represent one or two cases, but are composed of a 
number of figures, accurately colored, showing the appearance of various 
lesions, and will be found to give great aid in diagnosing. 

" This is one of the best of the smaller handbooks of dermatology that we have seen." — 
N. V. Medical Journal. 

TYSON ON THE URINE. Sixth Edition. A Practical Guide to the 
Examination of Urine. For the Use of Physicians and Students. By 
James Tyson, m.d., Prof, of Pathology and Morbid Anatomy in the Uni- 
versity of Pennsylvania. With Colored Lithographic Plates and Numerous 
Illustrations Engraved on Wood. Sixth Edition, Revised and Enlarged. 
I2mo. Cloth, £1. 50. 

"The practical man will find in this little book all that is absolutely necessary for him to 
know in order to utilize fully the data supplied by the urine." — Chicago Medical Journal. 

GILLIAM'S PATHOLOGY. The Essentials of Pathology; a Handbook 
for Students. By D. Tod Gilliam, m.d., Prof, of Physiology, Starling 
Medical College, Columbus, Ohio. With forty-seven Illustrations. i2mo. 
Cloth, $2.00. 

"Will be found useful by students who are commencing the study of pathology." — Dublin 
Journal 0/ Medical Sciences. 

"It is practically a student's book, and we have no hesitation in recommending it." — The- 
rapeutic Gazette. 

WOLFF'S APPLIED MEDICAL CHEMISTRY. Containing a De- 
scription of the Apparatus and Methods Employed in the Practice of Med- 
ical Chemistry, the Chemistry of Poisons, Physiological and Pathological 
Analysis, Urinary and Fecal Analysis, Sanitary Chemistry and the Exami- 
nation of Medicinal Agents, Foods, etc. By Lawrence Wolff, m.d., 
Demonstrator of Chemistry in the Jefferson Medical College; Member of 
the Philadelphia College of Pharmacy, etc. 8vo. Cloth, $1. 00. 
*** The object of the author of this book is to furnish the practitioner and 
student a reliable and simple guide for making analyses and examinations of 
the various medicinal agents, human excretions, secretions, etc., without elab- 
orate apparatus or expensive processes. 



P. BLAKISTON, SON & CO., Publishers and Booksellers, 

1012 WALNUT STREET, PHILADELPHIA. 



Standard Text-Books. 

LANDOIS' HUMAN PHYSIOLOGY. A Text-Book of Human Physi- 
ology, including Histology and Microscopical Anatomy, with special 
reference to the requirements of Practical Medicine. By Dr. L. 
Landois, Professor of Physiology and Director of the Physiological Insti- 
tute, University of Greifswald. Translated from the Fifth German Edition, 
with additions by Wm. Stirling, m.d., Sc.d., Brackenburg, Professor of 
Physiology and Histology in Owen's College and Victoria University, Man- 
chester ; Examiner in the Honors' School of Science, University of Ox- 
ford, England. Third Edition, revised and enlarged. 692 Illustrations. 
One Volume. Royal Octavo. Cloth, $6.50; Leather, $7.50. 

"With this Text-book at command, no Student could fail in his examination."— 
The Lancet. 

" One of the most practical works on Physiology ever written, forming a 'bridge ' be- 
tween Physiology and Practical Medicine. ... Its chief merits are its completeness and 
conciseness. . . . Excellently clear, attractive and succinct." — British Medical 
Journal. 

" Unquestionably the most admirable exposition of the relations of Human Physiology to 
Practical Medicine ever laid before English readers." — Students' Journal. 

" Landois' Physiology is, without question, the best text-book on the subject that has ever 
been written." — New York Medical Record, 

CAZEAUX AND TARNIER'S MIDWIFERY. Eighth Revised 
and Enlarged Edition. With Appendix, by Munde. The Theory 
and Practice of Obstetrics; including the Diseases of Pregnancy and 
Parturition, Obstetrical Operations, etc. By P. Cazeaux, Member of 
the Imperial Academy of Medicine. Remodeled and rearranged, with 
revisions and additions, by S. Tarnier, m.d., Prof, of Obstetrics and 
Diseases of Women and Children in the Faculty of Medicine of Paris. 
Eighth American, from the Eighth French and First Italian Editions. 
Edited and Enlarged by Robert J. Hess, m.d., Physician to the Northern 
Dispensary, Phila., etc., with an Appendix by Paul F. Munde, m.d., 
Professor of Gynaecology at the New York Polyclinic, Vice-President 
American Gynaecological Society, etc. With Chromo- lithographs, Litho- 
graphs, and other Full-page Plates, seven of which are beautifully colored, 
and numerous Wood Engravings. One Volume, octavo. 

Cloth, $5.00; Full Leather, $6.00. 

MEYER ON DISEASES OF THE EYE. A Manual of Ophthal- 
mology. By Dr. Edouard Meyer, Prof, a l'fecole Pratique de la Faculty 
MSdecine de Paris ; Chevalier of the Legion of Honor, etc. Translated 
from the Third French Edition, with the assistance of the author, by Dr. 
Freeland Fergus, Assistant Surgeon, Glasgow Eye Infirmary. With 267 
Illustrations and three Colored Plates. Prepared under the direction of Dr. 
R. Liebreich. 8vo. Cloth, #4.50; Leather, $5.50. 
The first chapter is an explanation of the best means for examining the eyes, 
externally and internally, with a view to diagnosis, the various ophthalmo- 
scopes, general considerations on the treatment of ophthalmia, etc. Each dis- 
ease is then taken up in its proper order ; the anatomy of the part being pre- 
sented first, followed by the diagnosis, causes, progress, prognosis, etiology and 
treatment. The arrangement of the work will thus be seen to be systematic, 
commending itself to all physicians and students for the logical and concise 
way in which the facts are given. This English edition makes the eighth 
language into which Meyer's book has been translated. 

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Standard Text-Books. 

HOLDEN'S ANATOMY. A Manual of the Dissections of the Human 
Body. By Luther Holden, f.r.c.s. Fifth Edition. Carefully Revised 
and Enlarged, specially concerning the Anatomy of the Nervous System 
Organs of Special Sense, etc. By John Langton, f.r.c.s., Surgeon to, 
and Lecturer on Anatomy at, St. Bartholomew's Hospital. 208 Illustrations. 
8vo. Cloth, $5.00; Leather, $6.00. 

Oil-cloth Covers, for the Dissecting Room, £4.50. 

The popularity of this work has steadily increased during the past few years. It is proba- 
bly used more extensively than any other dissector. The Oil-cloth binding allows of wash- 
ing, and does not retain the dirt and odor of the dissecting table. This edition has been 
carefully printed and bound, and lays open flat at any page. 

" No student of anatomy can take up this book without being pleased and instructed. Its 
diagrams are original, striking and suggestive, giving more at a glance than pages of text 
description. All this is known to those who are already acquainted with this admirable 
work; but it is simpe justice to its value, as a work for careful study and reference, that 
these points be emphasized to such as are commencing their studies. The text matches the 
illustrations in directness of practical application and clearness of detail." — New York Med- 
ical Record. 

ANDERSON ON SKIN DISEASES. A complete Treatise on Skin 
Diseases. By McCall Anderson, m.d., Professor of Clinical Medicine, 
University of Glasgow. With numerous wood engravings and several col- 
ored and steel plates. Octavo. Cloth, $4.50. Leather, $5.50. Just Ready. 

This aims to be a complete text-book. It will be found to contain all the latest methods 
of treatment. The subject is dealt with in a systematic, practical manner, and is based on 
an extensive experience of nearly twenty-five years. 

GOWERS' MANUAL OF DISEASES OF THE NERVOUS 
SYSTEM. A Complete Text-book. By William R. Gowers, m.d., 
Professor Clinical Medicine, University College, London. Physician to 
National Hospital for the Paralyzed and Epileptic. Comprising over 
400 Illustrations and 1360 pages. Octavo. Cloth, $6.50; Leather, $7.50. 

BYFORD. DISEASES OF WOMEN. The Practice of Medicine and 

Surgery, as applied to the Diseases and Accidents Incident to Women. 

By W. H. Byford, a.m., m.d., Professor of Gynaecology in Rush Medical 

College and of Obstetrics in the Woman's Medical College ; Surgeon to 

the Woman's Hospital; Ex President American Gynaecological Society, 

etc. ; and Henry T. Byford, m.d., Surgeon to the Woman's Hospital 

of Chicago ; Gynaecologist to St. Luke's Hospital ; President Chicago 

Gynaecological Society, etc. Fourth Edition, Revised, Rewritten and 

Enlarged. With 306 Illustrations, over 100 of which are original. Octavo. 

832 pages. Cloth, $5.00; Leather, $6.00. 

" In short, the book is brought up to the standard of to-day, and in most respects may be 
considered a reliable, practical text-book, written by an earnest worker and practical man." 
'—American Journal 0/ Medical Sciences. 

ROBERTS. PRACTICE OF MEDICINE. The Theory and Prac- 
tice of Medicine. By Frederick Roberts, m.d., Professor of Thera- 
peutics at University College, London. Seventh American Edition, 
thoroughly revised and enlarged, with new Illustrations. 8vo. Cloth, 
$5.50; Leather, #6.50. 

" If there is a book in the whole of medical literature in which so much is said in so few 
words, it has never come within our reach." — Chicago Medical Journal. 

" The best text-book for students. We know of no work in the English language, or of 
any other, which competes with this one." — Edinburgh Medical Journal. 

P. BLAKISTON, SON & CO., Publishers and Booksellers, 
1012 WALNUT STREET, PHILADELPHIA.